1 //===- AddressSanitizer.cpp - memory error detector -----------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file is a part of AddressSanitizer, an address sanity checker.
10 // Details of the algorithm:
11 // https://github.com/google/sanitizers/wiki/AddressSanitizerAlgorithm
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "llvm/Transforms/Instrumentation/AddressSanitizer.h"
16 #include "llvm/ADT/ArrayRef.h"
17 #include "llvm/ADT/DenseMap.h"
18 #include "llvm/ADT/DepthFirstIterator.h"
19 #include "llvm/ADT/SmallPtrSet.h"
20 #include "llvm/ADT/SmallVector.h"
21 #include "llvm/ADT/Statistic.h"
22 #include "llvm/ADT/StringExtras.h"
23 #include "llvm/ADT/StringRef.h"
24 #include "llvm/ADT/Triple.h"
25 #include "llvm/ADT/Twine.h"
26 #include "llvm/Analysis/MemoryBuiltins.h"
27 #include "llvm/Analysis/TargetLibraryInfo.h"
28 #include "llvm/Analysis/ValueTracking.h"
29 #include "llvm/BinaryFormat/MachO.h"
30 #include "llvm/IR/Argument.h"
31 #include "llvm/IR/Attributes.h"
32 #include "llvm/IR/BasicBlock.h"
33 #include "llvm/IR/CallSite.h"
34 #include "llvm/IR/Comdat.h"
35 #include "llvm/IR/Constant.h"
36 #include "llvm/IR/Constants.h"
37 #include "llvm/IR/DIBuilder.h"
38 #include "llvm/IR/DataLayout.h"
39 #include "llvm/IR/DebugInfoMetadata.h"
40 #include "llvm/IR/DebugLoc.h"
41 #include "llvm/IR/DerivedTypes.h"
42 #include "llvm/IR/Dominators.h"
43 #include "llvm/IR/Function.h"
44 #include "llvm/IR/GlobalAlias.h"
45 #include "llvm/IR/GlobalValue.h"
46 #include "llvm/IR/GlobalVariable.h"
47 #include "llvm/IR/IRBuilder.h"
48 #include "llvm/IR/InlineAsm.h"
49 #include "llvm/IR/InstVisitor.h"
50 #include "llvm/IR/InstrTypes.h"
51 #include "llvm/IR/Instruction.h"
52 #include "llvm/IR/Instructions.h"
53 #include "llvm/IR/IntrinsicInst.h"
54 #include "llvm/IR/Intrinsics.h"
55 #include "llvm/IR/LLVMContext.h"
56 #include "llvm/IR/MDBuilder.h"
57 #include "llvm/IR/Metadata.h"
58 #include "llvm/IR/Module.h"
59 #include "llvm/IR/Type.h"
60 #include "llvm/IR/Use.h"
61 #include "llvm/IR/Value.h"
62 #include "llvm/InitializePasses.h"
63 #include "llvm/MC/MCSectionMachO.h"
64 #include "llvm/Pass.h"
65 #include "llvm/Support/Casting.h"
66 #include "llvm/Support/CommandLine.h"
67 #include "llvm/Support/Debug.h"
68 #include "llvm/Support/ErrorHandling.h"
69 #include "llvm/Support/MathExtras.h"
70 #include "llvm/Support/ScopedPrinter.h"
71 #include "llvm/Support/raw_ostream.h"
72 #include "llvm/Transforms/Instrumentation.h"
73 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
74 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
75 #include "llvm/Transforms/Utils/Local.h"
76 #include "llvm/Transforms/Utils/ModuleUtils.h"
77 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
78 #include <algorithm>
79 #include <cassert>
80 #include <cstddef>
81 #include <cstdint>
82 #include <iomanip>
83 #include <limits>
84 #include <memory>
85 #include <sstream>
86 #include <string>
87 #include <tuple>
88
89 using namespace llvm;
90
91 #define DEBUG_TYPE "asan"
92
93 static const uint64_t kDefaultShadowScale = 3;
94 static const uint64_t kDefaultShadowOffset32 = 1ULL << 29;
95 static const uint64_t kDefaultShadowOffset64 = 1ULL << 44;
96 static const uint64_t kDynamicShadowSentinel =
97 std::numeric_limits<uint64_t>::max();
98 static const uint64_t kSmallX86_64ShadowOffsetBase = 0x7FFFFFFF; // < 2G.
99 static const uint64_t kSmallX86_64ShadowOffsetAlignMask = ~0xFFFULL;
100 static const uint64_t kLinuxKasan_ShadowOffset64 = 0xdffffc0000000000;
101 static const uint64_t kPPC64_ShadowOffset64 = 1ULL << 44;
102 static const uint64_t kSystemZ_ShadowOffset64 = 1ULL << 52;
103 static const uint64_t kMIPS32_ShadowOffset32 = 0x0aaa0000;
104 static const uint64_t kMIPS64_ShadowOffset64 = 1ULL << 37;
105 static const uint64_t kAArch64_ShadowOffset64 = 1ULL << 36;
106 static const uint64_t kFreeBSD_ShadowOffset32 = 1ULL << 30;
107 static const uint64_t kFreeBSD_ShadowOffset64 = 1ULL << 46;
108 static const uint64_t kNetBSD_ShadowOffset32 = 1ULL << 30;
109 static const uint64_t kNetBSD_ShadowOffset64 = 1ULL << 46;
110 static const uint64_t kNetBSDKasan_ShadowOffset64 = 0xdfff900000000000;
111 static const uint64_t kPS4CPU_ShadowOffset64 = 1ULL << 40;
112 static const uint64_t kWindowsShadowOffset32 = 3ULL << 28;
113 static const uint64_t kEmscriptenShadowOffset = 0;
114
115 static const uint64_t kMyriadShadowScale = 5;
116 static const uint64_t kMyriadMemoryOffset32 = 0x80000000ULL;
117 static const uint64_t kMyriadMemorySize32 = 0x20000000ULL;
118 static const uint64_t kMyriadTagShift = 29;
119 static const uint64_t kMyriadDDRTag = 4;
120 static const uint64_t kMyriadCacheBitMask32 = 0x40000000ULL;
121
122 // The shadow memory space is dynamically allocated.
123 static const uint64_t kWindowsShadowOffset64 = kDynamicShadowSentinel;
124
125 static const size_t kMinStackMallocSize = 1 << 6; // 64B
126 static const size_t kMaxStackMallocSize = 1 << 16; // 64K
127 static const uintptr_t kCurrentStackFrameMagic = 0x41B58AB3;
128 static const uintptr_t kRetiredStackFrameMagic = 0x45E0360E;
129
130 static const char *const kAsanModuleCtorName = "asan.module_ctor";
131 static const char *const kAsanModuleDtorName = "asan.module_dtor";
132 static const uint64_t kAsanCtorAndDtorPriority = 1;
133 // On Emscripten, the system needs more than one priorities for constructors.
134 static const uint64_t kAsanEmscriptenCtorAndDtorPriority = 50;
135 static const char *const kAsanReportErrorTemplate = "__asan_report_";
136 static const char *const kAsanRegisterGlobalsName = "__asan_register_globals";
137 static const char *const kAsanUnregisterGlobalsName =
138 "__asan_unregister_globals";
139 static const char *const kAsanRegisterImageGlobalsName =
140 "__asan_register_image_globals";
141 static const char *const kAsanUnregisterImageGlobalsName =
142 "__asan_unregister_image_globals";
143 static const char *const kAsanRegisterElfGlobalsName =
144 "__asan_register_elf_globals";
145 static const char *const kAsanUnregisterElfGlobalsName =
146 "__asan_unregister_elf_globals";
147 static const char *const kAsanPoisonGlobalsName = "__asan_before_dynamic_init";
148 static const char *const kAsanUnpoisonGlobalsName = "__asan_after_dynamic_init";
149 static const char *const kAsanInitName = "__asan_init";
150 static const char *const kAsanVersionCheckNamePrefix =
151 "__asan_version_mismatch_check_v";
152 static const char *const kAsanPtrCmp = "__sanitizer_ptr_cmp";
153 static const char *const kAsanPtrSub = "__sanitizer_ptr_sub";
154 static const char *const kAsanHandleNoReturnName = "__asan_handle_no_return";
155 static const int kMaxAsanStackMallocSizeClass = 10;
156 static const char *const kAsanStackMallocNameTemplate = "__asan_stack_malloc_";
157 static const char *const kAsanStackFreeNameTemplate = "__asan_stack_free_";
158 static const char *const kAsanGenPrefix = "___asan_gen_";
159 static const char *const kODRGenPrefix = "__odr_asan_gen_";
160 static const char *const kSanCovGenPrefix = "__sancov_gen_";
161 static const char *const kAsanSetShadowPrefix = "__asan_set_shadow_";
162 static const char *const kAsanPoisonStackMemoryName =
163 "__asan_poison_stack_memory";
164 static const char *const kAsanUnpoisonStackMemoryName =
165 "__asan_unpoison_stack_memory";
166
167 // ASan version script has __asan_* wildcard. Triple underscore prevents a
168 // linker (gold) warning about attempting to export a local symbol.
169 static const char *const kAsanGlobalsRegisteredFlagName =
170 "___asan_globals_registered";
171
172 static const char *const kAsanOptionDetectUseAfterReturn =
173 "__asan_option_detect_stack_use_after_return";
174
175 static const char *const kAsanShadowMemoryDynamicAddress =
176 "__asan_shadow_memory_dynamic_address";
177
178 static const char *const kAsanAllocaPoison = "__asan_alloca_poison";
179 static const char *const kAsanAllocasUnpoison = "__asan_allocas_unpoison";
180
181 // Accesses sizes are powers of two: 1, 2, 4, 8, 16.
182 static const size_t kNumberOfAccessSizes = 5;
183
184 static const unsigned kAllocaRzSize = 32;
185
186 // Command-line flags.
187
188 static cl::opt<bool> ClEnableKasan(
189 "asan-kernel", cl::desc("Enable KernelAddressSanitizer instrumentation"),
190 cl::Hidden, cl::init(false));
191
192 static cl::opt<bool> ClRecover(
193 "asan-recover",
194 cl::desc("Enable recovery mode (continue-after-error)."),
195 cl::Hidden, cl::init(false));
196
197 static cl::opt<bool> ClInsertVersionCheck(
198 "asan-guard-against-version-mismatch",
199 cl::desc("Guard against compiler/runtime version mismatch."),
200 cl::Hidden, cl::init(true));
201
202 // This flag may need to be replaced with -f[no-]asan-reads.
203 static cl::opt<bool> ClInstrumentReads("asan-instrument-reads",
204 cl::desc("instrument read instructions"),
205 cl::Hidden, cl::init(true));
206
207 static cl::opt<bool> ClInstrumentWrites(
208 "asan-instrument-writes", cl::desc("instrument write instructions"),
209 cl::Hidden, cl::init(true));
210
211 static cl::opt<bool> ClInstrumentAtomics(
212 "asan-instrument-atomics",
213 cl::desc("instrument atomic instructions (rmw, cmpxchg)"), cl::Hidden,
214 cl::init(true));
215
216 static cl::opt<bool> ClAlwaysSlowPath(
217 "asan-always-slow-path",
218 cl::desc("use instrumentation with slow path for all accesses"), cl::Hidden,
219 cl::init(false));
220
221 static cl::opt<bool> ClForceDynamicShadow(
222 "asan-force-dynamic-shadow",
223 cl::desc("Load shadow address into a local variable for each function"),
224 cl::Hidden, cl::init(false));
225
226 static cl::opt<bool>
227 ClWithIfunc("asan-with-ifunc",
228 cl::desc("Access dynamic shadow through an ifunc global on "
229 "platforms that support this"),
230 cl::Hidden, cl::init(true));
231
232 static cl::opt<bool> ClWithIfuncSuppressRemat(
233 "asan-with-ifunc-suppress-remat",
234 cl::desc("Suppress rematerialization of dynamic shadow address by passing "
235 "it through inline asm in prologue."),
236 cl::Hidden, cl::init(true));
237
238 // This flag limits the number of instructions to be instrumented
239 // in any given BB. Normally, this should be set to unlimited (INT_MAX),
240 // but due to http://llvm.org/bugs/show_bug.cgi?id=12652 we temporary
241 // set it to 10000.
242 static cl::opt<int> ClMaxInsnsToInstrumentPerBB(
243 "asan-max-ins-per-bb", cl::init(10000),
244 cl::desc("maximal number of instructions to instrument in any given BB"),
245 cl::Hidden);
246
247 // This flag may need to be replaced with -f[no]asan-stack.
248 static cl::opt<bool> ClStack("asan-stack", cl::desc("Handle stack memory"),
249 cl::Hidden, cl::init(true));
250 static cl::opt<uint32_t> ClMaxInlinePoisoningSize(
251 "asan-max-inline-poisoning-size",
252 cl::desc(
253 "Inline shadow poisoning for blocks up to the given size in bytes."),
254 cl::Hidden, cl::init(64));
255
256 static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
257 cl::desc("Check stack-use-after-return"),
258 cl::Hidden, cl::init(true));
259
260 static cl::opt<bool> ClRedzoneByvalArgs("asan-redzone-byval-args",
261 cl::desc("Create redzones for byval "
262 "arguments (extra copy "
263 "required)"), cl::Hidden,
264 cl::init(true));
265
266 static cl::opt<bool> ClUseAfterScope("asan-use-after-scope",
267 cl::desc("Check stack-use-after-scope"),
268 cl::Hidden, cl::init(false));
269
270 // This flag may need to be replaced with -f[no]asan-globals.
271 static cl::opt<bool> ClGlobals("asan-globals",
272 cl::desc("Handle global objects"), cl::Hidden,
273 cl::init(true));
274
275 static cl::opt<bool> ClInitializers("asan-initialization-order",
276 cl::desc("Handle C++ initializer order"),
277 cl::Hidden, cl::init(true));
278
279 static cl::opt<bool> ClInvalidPointerPairs(
280 "asan-detect-invalid-pointer-pair",
281 cl::desc("Instrument <, <=, >, >=, - with pointer operands"), cl::Hidden,
282 cl::init(false));
283
284 static cl::opt<bool> ClInvalidPointerCmp(
285 "asan-detect-invalid-pointer-cmp",
286 cl::desc("Instrument <, <=, >, >= with pointer operands"), cl::Hidden,
287 cl::init(false));
288
289 static cl::opt<bool> ClInvalidPointerSub(
290 "asan-detect-invalid-pointer-sub",
291 cl::desc("Instrument - operations with pointer operands"), cl::Hidden,
292 cl::init(false));
293
294 static cl::opt<unsigned> ClRealignStack(
295 "asan-realign-stack",
296 cl::desc("Realign stack to the value of this flag (power of two)"),
297 cl::Hidden, cl::init(32));
298
299 static cl::opt<int> ClInstrumentationWithCallsThreshold(
300 "asan-instrumentation-with-call-threshold",
301 cl::desc(
302 "If the function being instrumented contains more than "
303 "this number of memory accesses, use callbacks instead of "
304 "inline checks (-1 means never use callbacks)."),
305 cl::Hidden, cl::init(7000));
306
307 static cl::opt<std::string> ClMemoryAccessCallbackPrefix(
308 "asan-memory-access-callback-prefix",
309 cl::desc("Prefix for memory access callbacks"), cl::Hidden,
310 cl::init("__asan_"));
311
312 static cl::opt<bool>
313 ClInstrumentDynamicAllocas("asan-instrument-dynamic-allocas",
314 cl::desc("instrument dynamic allocas"),
315 cl::Hidden, cl::init(true));
316
317 static cl::opt<bool> ClSkipPromotableAllocas(
318 "asan-skip-promotable-allocas",
319 cl::desc("Do not instrument promotable allocas"), cl::Hidden,
320 cl::init(true));
321
322 // These flags allow to change the shadow mapping.
323 // The shadow mapping looks like
324 // Shadow = (Mem >> scale) + offset
325
326 static cl::opt<int> ClMappingScale("asan-mapping-scale",
327 cl::desc("scale of asan shadow mapping"),
328 cl::Hidden, cl::init(0));
329
330 static cl::opt<uint64_t>
331 ClMappingOffset("asan-mapping-offset",
332 cl::desc("offset of asan shadow mapping [EXPERIMENTAL]"),
333 cl::Hidden, cl::init(0));
334
335 // Optimization flags. Not user visible, used mostly for testing
336 // and benchmarking the tool.
337
338 static cl::opt<bool> ClOpt("asan-opt", cl::desc("Optimize instrumentation"),
339 cl::Hidden, cl::init(true));
340
341 static cl::opt<bool> ClOptSameTemp(
342 "asan-opt-same-temp", cl::desc("Instrument the same temp just once"),
343 cl::Hidden, cl::init(true));
344
345 static cl::opt<bool> ClOptGlobals("asan-opt-globals",
346 cl::desc("Don't instrument scalar globals"),
347 cl::Hidden, cl::init(true));
348
349 static cl::opt<bool> ClOptStack(
350 "asan-opt-stack", cl::desc("Don't instrument scalar stack variables"),
351 cl::Hidden, cl::init(false));
352
353 static cl::opt<bool> ClDynamicAllocaStack(
354 "asan-stack-dynamic-alloca",
355 cl::desc("Use dynamic alloca to represent stack variables"), cl::Hidden,
356 cl::init(true));
357
358 static cl::opt<uint32_t> ClForceExperiment(
359 "asan-force-experiment",
360 cl::desc("Force optimization experiment (for testing)"), cl::Hidden,
361 cl::init(0));
362
363 static cl::opt<bool>
364 ClUsePrivateAlias("asan-use-private-alias",
365 cl::desc("Use private aliases for global variables"),
366 cl::Hidden, cl::init(false));
367
368 static cl::opt<bool>
369 ClUseOdrIndicator("asan-use-odr-indicator",
370 cl::desc("Use odr indicators to improve ODR reporting"),
371 cl::Hidden, cl::init(false));
372
373 static cl::opt<bool>
374 ClUseGlobalsGC("asan-globals-live-support",
375 cl::desc("Use linker features to support dead "
376 "code stripping of globals"),
377 cl::Hidden, cl::init(true));
378
379 // This is on by default even though there is a bug in gold:
380 // https://sourceware.org/bugzilla/show_bug.cgi?id=19002
381 static cl::opt<bool>
382 ClWithComdat("asan-with-comdat",
383 cl::desc("Place ASan constructors in comdat sections"),
384 cl::Hidden, cl::init(true));
385
386 // Debug flags.
387
388 static cl::opt<int> ClDebug("asan-debug", cl::desc("debug"), cl::Hidden,
389 cl::init(0));
390
391 static cl::opt<int> ClDebugStack("asan-debug-stack", cl::desc("debug stack"),
392 cl::Hidden, cl::init(0));
393
394 static cl::opt<std::string> ClDebugFunc("asan-debug-func", cl::Hidden,
395 cl::desc("Debug func"));
396
397 static cl::opt<int> ClDebugMin("asan-debug-min", cl::desc("Debug min inst"),
398 cl::Hidden, cl::init(-1));
399
400 static cl::opt<int> ClDebugMax("asan-debug-max", cl::desc("Debug max inst"),
401 cl::Hidden, cl::init(-1));
402
403 STATISTIC(NumInstrumentedReads, "Number of instrumented reads");
404 STATISTIC(NumInstrumentedWrites, "Number of instrumented writes");
405 STATISTIC(NumOptimizedAccessesToGlobalVar,
406 "Number of optimized accesses to global vars");
407 STATISTIC(NumOptimizedAccessesToStackVar,
408 "Number of optimized accesses to stack vars");
409
410 namespace {
411
412 /// This struct defines the shadow mapping using the rule:
413 /// shadow = (mem >> Scale) ADD-or-OR Offset.
414 /// If InGlobal is true, then
415 /// extern char __asan_shadow[];
416 /// shadow = (mem >> Scale) + &__asan_shadow
417 struct ShadowMapping {
418 int Scale;
419 uint64_t Offset;
420 bool OrShadowOffset;
421 bool InGlobal;
422 };
423
424 } // end anonymous namespace
425
getShadowMapping(Triple & TargetTriple,int LongSize,bool IsKasan)426 static ShadowMapping getShadowMapping(Triple &TargetTriple, int LongSize,
427 bool IsKasan) {
428 bool IsAndroid = TargetTriple.isAndroid();
429 bool IsIOS = TargetTriple.isiOS() || TargetTriple.isWatchOS();
430 bool IsFreeBSD = TargetTriple.isOSFreeBSD();
431 bool IsNetBSD = TargetTriple.isOSNetBSD();
432 bool IsPS4CPU = TargetTriple.isPS4CPU();
433 bool IsLinux = TargetTriple.isOSLinux();
434 bool IsPPC64 = TargetTriple.getArch() == Triple::ppc64 ||
435 TargetTriple.getArch() == Triple::ppc64le;
436 bool IsSystemZ = TargetTriple.getArch() == Triple::systemz;
437 bool IsX86_64 = TargetTriple.getArch() == Triple::x86_64;
438 bool IsMIPS32 = TargetTriple.isMIPS32();
439 bool IsMIPS64 = TargetTriple.isMIPS64();
440 bool IsArmOrThumb = TargetTriple.isARM() || TargetTriple.isThumb();
441 bool IsAArch64 = TargetTriple.getArch() == Triple::aarch64;
442 bool IsWindows = TargetTriple.isOSWindows();
443 bool IsFuchsia = TargetTriple.isOSFuchsia();
444 bool IsMyriad = TargetTriple.getVendor() == llvm::Triple::Myriad;
445 bool IsEmscripten = TargetTriple.isOSEmscripten();
446
447 ShadowMapping Mapping;
448
449 Mapping.Scale = IsMyriad ? kMyriadShadowScale : kDefaultShadowScale;
450 if (ClMappingScale.getNumOccurrences() > 0) {
451 Mapping.Scale = ClMappingScale;
452 }
453
454 if (LongSize == 32) {
455 if (IsAndroid)
456 Mapping.Offset = kDynamicShadowSentinel;
457 else if (IsMIPS32)
458 Mapping.Offset = kMIPS32_ShadowOffset32;
459 else if (IsFreeBSD)
460 Mapping.Offset = kFreeBSD_ShadowOffset32;
461 else if (IsNetBSD)
462 Mapping.Offset = kNetBSD_ShadowOffset32;
463 else if (IsIOS)
464 Mapping.Offset = kDynamicShadowSentinel;
465 else if (IsWindows)
466 Mapping.Offset = kWindowsShadowOffset32;
467 else if (IsEmscripten)
468 Mapping.Offset = kEmscriptenShadowOffset;
469 else if (IsMyriad) {
470 uint64_t ShadowOffset = (kMyriadMemoryOffset32 + kMyriadMemorySize32 -
471 (kMyriadMemorySize32 >> Mapping.Scale));
472 Mapping.Offset = ShadowOffset - (kMyriadMemoryOffset32 >> Mapping.Scale);
473 }
474 else
475 Mapping.Offset = kDefaultShadowOffset32;
476 } else { // LongSize == 64
477 // Fuchsia is always PIE, which means that the beginning of the address
478 // space is always available.
479 if (IsFuchsia)
480 Mapping.Offset = 0;
481 else if (IsPPC64)
482 Mapping.Offset = kPPC64_ShadowOffset64;
483 else if (IsSystemZ)
484 Mapping.Offset = kSystemZ_ShadowOffset64;
485 else if (IsFreeBSD && !IsMIPS64)
486 Mapping.Offset = kFreeBSD_ShadowOffset64;
487 else if (IsNetBSD) {
488 if (IsKasan)
489 Mapping.Offset = kNetBSDKasan_ShadowOffset64;
490 else
491 Mapping.Offset = kNetBSD_ShadowOffset64;
492 } else if (IsPS4CPU)
493 Mapping.Offset = kPS4CPU_ShadowOffset64;
494 else if (IsLinux && IsX86_64) {
495 if (IsKasan)
496 Mapping.Offset = kLinuxKasan_ShadowOffset64;
497 else
498 Mapping.Offset = (kSmallX86_64ShadowOffsetBase &
499 (kSmallX86_64ShadowOffsetAlignMask << Mapping.Scale));
500 } else if (IsWindows && IsX86_64) {
501 Mapping.Offset = kWindowsShadowOffset64;
502 } else if (IsMIPS64)
503 Mapping.Offset = kMIPS64_ShadowOffset64;
504 else if (IsIOS)
505 Mapping.Offset = kDynamicShadowSentinel;
506 else if (IsAArch64)
507 Mapping.Offset = kAArch64_ShadowOffset64;
508 else
509 Mapping.Offset = kDefaultShadowOffset64;
510 }
511
512 if (ClForceDynamicShadow) {
513 Mapping.Offset = kDynamicShadowSentinel;
514 }
515
516 if (ClMappingOffset.getNumOccurrences() > 0) {
517 Mapping.Offset = ClMappingOffset;
518 }
519
520 // OR-ing shadow offset if more efficient (at least on x86) if the offset
521 // is a power of two, but on ppc64 we have to use add since the shadow
522 // offset is not necessary 1/8-th of the address space. On SystemZ,
523 // we could OR the constant in a single instruction, but it's more
524 // efficient to load it once and use indexed addressing.
525 Mapping.OrShadowOffset = !IsAArch64 && !IsPPC64 && !IsSystemZ && !IsPS4CPU &&
526 !(Mapping.Offset & (Mapping.Offset - 1)) &&
527 Mapping.Offset != kDynamicShadowSentinel;
528 bool IsAndroidWithIfuncSupport =
529 IsAndroid && !TargetTriple.isAndroidVersionLT(21);
530 Mapping.InGlobal = ClWithIfunc && IsAndroidWithIfuncSupport && IsArmOrThumb;
531
532 return Mapping;
533 }
534
RedzoneSizeForScale(int MappingScale)535 static size_t RedzoneSizeForScale(int MappingScale) {
536 // Redzone used for stack and globals is at least 32 bytes.
537 // For scales 6 and 7, the redzone has to be 64 and 128 bytes respectively.
538 return std::max(32U, 1U << MappingScale);
539 }
540
GetCtorAndDtorPriority(Triple & TargetTriple)541 static uint64_t GetCtorAndDtorPriority(Triple &TargetTriple) {
542 if (TargetTriple.isOSEmscripten()) {
543 return kAsanEmscriptenCtorAndDtorPriority;
544 } else {
545 return kAsanCtorAndDtorPriority;
546 }
547 }
548
549 namespace {
550
551 /// Module analysis for getting various metadata about the module.
552 class ASanGlobalsMetadataWrapperPass : public ModulePass {
553 public:
554 static char ID;
555
ASanGlobalsMetadataWrapperPass()556 ASanGlobalsMetadataWrapperPass() : ModulePass(ID) {
557 initializeASanGlobalsMetadataWrapperPassPass(
558 *PassRegistry::getPassRegistry());
559 }
560
runOnModule(Module & M)561 bool runOnModule(Module &M) override {
562 GlobalsMD = GlobalsMetadata(M);
563 return false;
564 }
565
getPassName() const566 StringRef getPassName() const override {
567 return "ASanGlobalsMetadataWrapperPass";
568 }
569
getAnalysisUsage(AnalysisUsage & AU) const570 void getAnalysisUsage(AnalysisUsage &AU) const override {
571 AU.setPreservesAll();
572 }
573
getGlobalsMD()574 GlobalsMetadata &getGlobalsMD() { return GlobalsMD; }
575
576 private:
577 GlobalsMetadata GlobalsMD;
578 };
579
580 char ASanGlobalsMetadataWrapperPass::ID = 0;
581
582 /// AddressSanitizer: instrument the code in module to find memory bugs.
583 struct AddressSanitizer {
AddressSanitizer__anond17fa1a10211::AddressSanitizer584 AddressSanitizer(Module &M, const GlobalsMetadata *GlobalsMD,
585 bool CompileKernel = false, bool Recover = false,
586 bool UseAfterScope = false)
587 : UseAfterScope(UseAfterScope || ClUseAfterScope), GlobalsMD(*GlobalsMD) {
588 this->Recover = ClRecover.getNumOccurrences() > 0 ? ClRecover : Recover;
589 this->CompileKernel =
590 ClEnableKasan.getNumOccurrences() > 0 ? ClEnableKasan : CompileKernel;
591
592 C = &(M.getContext());
593 LongSize = M.getDataLayout().getPointerSizeInBits();
594 IntptrTy = Type::getIntNTy(*C, LongSize);
595 TargetTriple = Triple(M.getTargetTriple());
596
597 Mapping = getShadowMapping(TargetTriple, LongSize, this->CompileKernel);
598 }
599
getAllocaSizeInBytes__anond17fa1a10211::AddressSanitizer600 uint64_t getAllocaSizeInBytes(const AllocaInst &AI) const {
601 uint64_t ArraySize = 1;
602 if (AI.isArrayAllocation()) {
603 const ConstantInt *CI = dyn_cast<ConstantInt>(AI.getArraySize());
604 assert(CI && "non-constant array size");
605 ArraySize = CI->getZExtValue();
606 }
607 Type *Ty = AI.getAllocatedType();
608 uint64_t SizeInBytes =
609 AI.getModule()->getDataLayout().getTypeAllocSize(Ty);
610 return SizeInBytes * ArraySize;
611 }
612
613 /// Check if we want (and can) handle this alloca.
614 bool isInterestingAlloca(const AllocaInst &AI);
615
616 /// If it is an interesting memory access, return the PointerOperand
617 /// and set IsWrite/Alignment. Otherwise return nullptr.
618 /// MaybeMask is an output parameter for the mask Value, if we're looking at a
619 /// masked load/store.
620 Value *isInterestingMemoryAccess(Instruction *I, bool *IsWrite,
621 uint64_t *TypeSize, unsigned *Alignment,
622 Value **MaybeMask = nullptr);
623
624 void instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis, Instruction *I,
625 bool UseCalls, const DataLayout &DL);
626 void instrumentPointerComparisonOrSubtraction(Instruction *I);
627 void instrumentAddress(Instruction *OrigIns, Instruction *InsertBefore,
628 Value *Addr, uint32_t TypeSize, bool IsWrite,
629 Value *SizeArgument, bool UseCalls, uint32_t Exp);
630 void instrumentUnusualSizeOrAlignment(Instruction *I,
631 Instruction *InsertBefore, Value *Addr,
632 uint32_t TypeSize, bool IsWrite,
633 Value *SizeArgument, bool UseCalls,
634 uint32_t Exp);
635 Value *createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
636 Value *ShadowValue, uint32_t TypeSize);
637 Instruction *generateCrashCode(Instruction *InsertBefore, Value *Addr,
638 bool IsWrite, size_t AccessSizeIndex,
639 Value *SizeArgument, uint32_t Exp);
640 void instrumentMemIntrinsic(MemIntrinsic *MI);
641 Value *memToShadow(Value *Shadow, IRBuilder<> &IRB);
642 bool instrumentFunction(Function &F, const TargetLibraryInfo *TLI);
643 bool maybeInsertAsanInitAtFunctionEntry(Function &F);
644 void maybeInsertDynamicShadowAtFunctionEntry(Function &F);
645 void markEscapedLocalAllocas(Function &F);
646
647 private:
648 friend struct FunctionStackPoisoner;
649
650 void initializeCallbacks(Module &M);
651
652 bool LooksLikeCodeInBug11395(Instruction *I);
653 bool GlobalIsLinkerInitialized(GlobalVariable *G);
654 bool isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis, Value *Addr,
655 uint64_t TypeSize) const;
656
657 /// Helper to cleanup per-function state.
658 struct FunctionStateRAII {
659 AddressSanitizer *Pass;
660
FunctionStateRAII__anond17fa1a10211::AddressSanitizer::FunctionStateRAII661 FunctionStateRAII(AddressSanitizer *Pass) : Pass(Pass) {
662 assert(Pass->ProcessedAllocas.empty() &&
663 "last pass forgot to clear cache");
664 assert(!Pass->LocalDynamicShadow);
665 }
666
~FunctionStateRAII__anond17fa1a10211::AddressSanitizer::FunctionStateRAII667 ~FunctionStateRAII() {
668 Pass->LocalDynamicShadow = nullptr;
669 Pass->ProcessedAllocas.clear();
670 }
671 };
672
673 LLVMContext *C;
674 Triple TargetTriple;
675 int LongSize;
676 bool CompileKernel;
677 bool Recover;
678 bool UseAfterScope;
679 Type *IntptrTy;
680 ShadowMapping Mapping;
681 FunctionCallee AsanHandleNoReturnFunc;
682 FunctionCallee AsanPtrCmpFunction, AsanPtrSubFunction;
683 Constant *AsanShadowGlobal;
684
685 // These arrays is indexed by AccessIsWrite, Experiment and log2(AccessSize).
686 FunctionCallee AsanErrorCallback[2][2][kNumberOfAccessSizes];
687 FunctionCallee AsanMemoryAccessCallback[2][2][kNumberOfAccessSizes];
688
689 // These arrays is indexed by AccessIsWrite and Experiment.
690 FunctionCallee AsanErrorCallbackSized[2][2];
691 FunctionCallee AsanMemoryAccessCallbackSized[2][2];
692
693 FunctionCallee AsanMemmove, AsanMemcpy, AsanMemset;
694 InlineAsm *EmptyAsm;
695 Value *LocalDynamicShadow = nullptr;
696 const GlobalsMetadata &GlobalsMD;
697 DenseMap<const AllocaInst *, bool> ProcessedAllocas;
698 };
699
700 class AddressSanitizerLegacyPass : public FunctionPass {
701 public:
702 static char ID;
703
AddressSanitizerLegacyPass(bool CompileKernel=false,bool Recover=false,bool UseAfterScope=false)704 explicit AddressSanitizerLegacyPass(bool CompileKernel = false,
705 bool Recover = false,
706 bool UseAfterScope = false)
707 : FunctionPass(ID), CompileKernel(CompileKernel), Recover(Recover),
708 UseAfterScope(UseAfterScope) {
709 initializeAddressSanitizerLegacyPassPass(*PassRegistry::getPassRegistry());
710 }
711
getPassName() const712 StringRef getPassName() const override {
713 return "AddressSanitizerFunctionPass";
714 }
715
getAnalysisUsage(AnalysisUsage & AU) const716 void getAnalysisUsage(AnalysisUsage &AU) const override {
717 AU.addRequired<ASanGlobalsMetadataWrapperPass>();
718 AU.addRequired<TargetLibraryInfoWrapperPass>();
719 }
720
runOnFunction(Function & F)721 bool runOnFunction(Function &F) override {
722 GlobalsMetadata &GlobalsMD =
723 getAnalysis<ASanGlobalsMetadataWrapperPass>().getGlobalsMD();
724 const TargetLibraryInfo *TLI =
725 &getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
726 AddressSanitizer ASan(*F.getParent(), &GlobalsMD, CompileKernel, Recover,
727 UseAfterScope);
728 return ASan.instrumentFunction(F, TLI);
729 }
730
731 private:
732 bool CompileKernel;
733 bool Recover;
734 bool UseAfterScope;
735 };
736
737 class ModuleAddressSanitizer {
738 public:
ModuleAddressSanitizer(Module & M,const GlobalsMetadata * GlobalsMD,bool CompileKernel=false,bool Recover=false,bool UseGlobalsGC=true,bool UseOdrIndicator=false)739 ModuleAddressSanitizer(Module &M, const GlobalsMetadata *GlobalsMD,
740 bool CompileKernel = false, bool Recover = false,
741 bool UseGlobalsGC = true, bool UseOdrIndicator = false)
742 : GlobalsMD(*GlobalsMD), UseGlobalsGC(UseGlobalsGC && ClUseGlobalsGC),
743 // Enable aliases as they should have no downside with ODR indicators.
744 UsePrivateAlias(UseOdrIndicator || ClUsePrivateAlias),
745 UseOdrIndicator(UseOdrIndicator || ClUseOdrIndicator),
746 // Not a typo: ClWithComdat is almost completely pointless without
747 // ClUseGlobalsGC (because then it only works on modules without
748 // globals, which are rare); it is a prerequisite for ClUseGlobalsGC;
749 // and both suffer from gold PR19002 for which UseGlobalsGC constructor
750 // argument is designed as workaround. Therefore, disable both
751 // ClWithComdat and ClUseGlobalsGC unless the frontend says it's ok to
752 // do globals-gc.
753 UseCtorComdat(UseGlobalsGC && ClWithComdat) {
754 this->Recover = ClRecover.getNumOccurrences() > 0 ? ClRecover : Recover;
755 this->CompileKernel =
756 ClEnableKasan.getNumOccurrences() > 0 ? ClEnableKasan : CompileKernel;
757
758 C = &(M.getContext());
759 int LongSize = M.getDataLayout().getPointerSizeInBits();
760 IntptrTy = Type::getIntNTy(*C, LongSize);
761 TargetTriple = Triple(M.getTargetTriple());
762 Mapping = getShadowMapping(TargetTriple, LongSize, this->CompileKernel);
763 }
764
765 bool instrumentModule(Module &);
766
767 private:
768 void initializeCallbacks(Module &M);
769
770 bool InstrumentGlobals(IRBuilder<> &IRB, Module &M, bool *CtorComdat);
771 void InstrumentGlobalsCOFF(IRBuilder<> &IRB, Module &M,
772 ArrayRef<GlobalVariable *> ExtendedGlobals,
773 ArrayRef<Constant *> MetadataInitializers);
774 void InstrumentGlobalsELF(IRBuilder<> &IRB, Module &M,
775 ArrayRef<GlobalVariable *> ExtendedGlobals,
776 ArrayRef<Constant *> MetadataInitializers,
777 const std::string &UniqueModuleId);
778 void InstrumentGlobalsMachO(IRBuilder<> &IRB, Module &M,
779 ArrayRef<GlobalVariable *> ExtendedGlobals,
780 ArrayRef<Constant *> MetadataInitializers);
781 void
782 InstrumentGlobalsWithMetadataArray(IRBuilder<> &IRB, Module &M,
783 ArrayRef<GlobalVariable *> ExtendedGlobals,
784 ArrayRef<Constant *> MetadataInitializers);
785
786 GlobalVariable *CreateMetadataGlobal(Module &M, Constant *Initializer,
787 StringRef OriginalName);
788 void SetComdatForGlobalMetadata(GlobalVariable *G, GlobalVariable *Metadata,
789 StringRef InternalSuffix);
790 IRBuilder<> CreateAsanModuleDtor(Module &M);
791
792 bool ShouldInstrumentGlobal(GlobalVariable *G);
793 bool ShouldUseMachOGlobalsSection() const;
794 StringRef getGlobalMetadataSection() const;
795 void poisonOneInitializer(Function &GlobalInit, GlobalValue *ModuleName);
796 void createInitializerPoisonCalls(Module &M, GlobalValue *ModuleName);
MinRedzoneSizeForGlobal() const797 size_t MinRedzoneSizeForGlobal() const {
798 return RedzoneSizeForScale(Mapping.Scale);
799 }
800 int GetAsanVersion(const Module &M) const;
801
802 const GlobalsMetadata &GlobalsMD;
803 bool CompileKernel;
804 bool Recover;
805 bool UseGlobalsGC;
806 bool UsePrivateAlias;
807 bool UseOdrIndicator;
808 bool UseCtorComdat;
809 Type *IntptrTy;
810 LLVMContext *C;
811 Triple TargetTriple;
812 ShadowMapping Mapping;
813 FunctionCallee AsanPoisonGlobals;
814 FunctionCallee AsanUnpoisonGlobals;
815 FunctionCallee AsanRegisterGlobals;
816 FunctionCallee AsanUnregisterGlobals;
817 FunctionCallee AsanRegisterImageGlobals;
818 FunctionCallee AsanUnregisterImageGlobals;
819 FunctionCallee AsanRegisterElfGlobals;
820 FunctionCallee AsanUnregisterElfGlobals;
821
822 Function *AsanCtorFunction = nullptr;
823 Function *AsanDtorFunction = nullptr;
824 };
825
826 class ModuleAddressSanitizerLegacyPass : public ModulePass {
827 public:
828 static char ID;
829
ModuleAddressSanitizerLegacyPass(bool CompileKernel=false,bool Recover=false,bool UseGlobalGC=true,bool UseOdrIndicator=false)830 explicit ModuleAddressSanitizerLegacyPass(bool CompileKernel = false,
831 bool Recover = false,
832 bool UseGlobalGC = true,
833 bool UseOdrIndicator = false)
834 : ModulePass(ID), CompileKernel(CompileKernel), Recover(Recover),
835 UseGlobalGC(UseGlobalGC), UseOdrIndicator(UseOdrIndicator) {
836 initializeModuleAddressSanitizerLegacyPassPass(
837 *PassRegistry::getPassRegistry());
838 }
839
getPassName() const840 StringRef getPassName() const override { return "ModuleAddressSanitizer"; }
841
getAnalysisUsage(AnalysisUsage & AU) const842 void getAnalysisUsage(AnalysisUsage &AU) const override {
843 AU.addRequired<ASanGlobalsMetadataWrapperPass>();
844 }
845
runOnModule(Module & M)846 bool runOnModule(Module &M) override {
847 GlobalsMetadata &GlobalsMD =
848 getAnalysis<ASanGlobalsMetadataWrapperPass>().getGlobalsMD();
849 ModuleAddressSanitizer ASanModule(M, &GlobalsMD, CompileKernel, Recover,
850 UseGlobalGC, UseOdrIndicator);
851 return ASanModule.instrumentModule(M);
852 }
853
854 private:
855 bool CompileKernel;
856 bool Recover;
857 bool UseGlobalGC;
858 bool UseOdrIndicator;
859 };
860
861 // Stack poisoning does not play well with exception handling.
862 // When an exception is thrown, we essentially bypass the code
863 // that unpoisones the stack. This is why the run-time library has
864 // to intercept __cxa_throw (as well as longjmp, etc) and unpoison the entire
865 // stack in the interceptor. This however does not work inside the
866 // actual function which catches the exception. Most likely because the
867 // compiler hoists the load of the shadow value somewhere too high.
868 // This causes asan to report a non-existing bug on 453.povray.
869 // It sounds like an LLVM bug.
870 struct FunctionStackPoisoner : public InstVisitor<FunctionStackPoisoner> {
871 Function &F;
872 AddressSanitizer &ASan;
873 DIBuilder DIB;
874 LLVMContext *C;
875 Type *IntptrTy;
876 Type *IntptrPtrTy;
877 ShadowMapping Mapping;
878
879 SmallVector<AllocaInst *, 16> AllocaVec;
880 SmallVector<AllocaInst *, 16> StaticAllocasToMoveUp;
881 SmallVector<Instruction *, 8> RetVec;
882 unsigned StackAlignment;
883
884 FunctionCallee AsanStackMallocFunc[kMaxAsanStackMallocSizeClass + 1],
885 AsanStackFreeFunc[kMaxAsanStackMallocSizeClass + 1];
886 FunctionCallee AsanSetShadowFunc[0x100] = {};
887 FunctionCallee AsanPoisonStackMemoryFunc, AsanUnpoisonStackMemoryFunc;
888 FunctionCallee AsanAllocaPoisonFunc, AsanAllocasUnpoisonFunc;
889
890 // Stores a place and arguments of poisoning/unpoisoning call for alloca.
891 struct AllocaPoisonCall {
892 IntrinsicInst *InsBefore;
893 AllocaInst *AI;
894 uint64_t Size;
895 bool DoPoison;
896 };
897 SmallVector<AllocaPoisonCall, 8> DynamicAllocaPoisonCallVec;
898 SmallVector<AllocaPoisonCall, 8> StaticAllocaPoisonCallVec;
899 bool HasUntracedLifetimeIntrinsic = false;
900
901 SmallVector<AllocaInst *, 1> DynamicAllocaVec;
902 SmallVector<IntrinsicInst *, 1> StackRestoreVec;
903 AllocaInst *DynamicAllocaLayout = nullptr;
904 IntrinsicInst *LocalEscapeCall = nullptr;
905
906 // Maps Value to an AllocaInst from which the Value is originated.
907 using AllocaForValueMapTy = DenseMap<Value *, AllocaInst *>;
908 AllocaForValueMapTy AllocaForValue;
909
910 bool HasNonEmptyInlineAsm = false;
911 bool HasReturnsTwiceCall = false;
912 std::unique_ptr<CallInst> EmptyInlineAsm;
913
FunctionStackPoisoner__anond17fa1a10211::FunctionStackPoisoner914 FunctionStackPoisoner(Function &F, AddressSanitizer &ASan)
915 : F(F), ASan(ASan), DIB(*F.getParent(), /*AllowUnresolved*/ false),
916 C(ASan.C), IntptrTy(ASan.IntptrTy),
917 IntptrPtrTy(PointerType::get(IntptrTy, 0)), Mapping(ASan.Mapping),
918 StackAlignment(1 << Mapping.Scale),
919 EmptyInlineAsm(CallInst::Create(ASan.EmptyAsm)) {}
920
runOnFunction__anond17fa1a10211::FunctionStackPoisoner921 bool runOnFunction() {
922 if (!ClStack) return false;
923
924 if (ClRedzoneByvalArgs)
925 copyArgsPassedByValToAllocas();
926
927 // Collect alloca, ret, lifetime instructions etc.
928 for (BasicBlock *BB : depth_first(&F.getEntryBlock())) visit(*BB);
929
930 if (AllocaVec.empty() && DynamicAllocaVec.empty()) return false;
931
932 initializeCallbacks(*F.getParent());
933
934 if (HasUntracedLifetimeIntrinsic) {
935 // If there are lifetime intrinsics which couldn't be traced back to an
936 // alloca, we may not know exactly when a variable enters scope, and
937 // therefore should "fail safe" by not poisoning them.
938 StaticAllocaPoisonCallVec.clear();
939 DynamicAllocaPoisonCallVec.clear();
940 }
941
942 processDynamicAllocas();
943 processStaticAllocas();
944
945 if (ClDebugStack) {
946 LLVM_DEBUG(dbgs() << F);
947 }
948 return true;
949 }
950
951 // Arguments marked with the "byval" attribute are implicitly copied without
952 // using an alloca instruction. To produce redzones for those arguments, we
953 // copy them a second time into memory allocated with an alloca instruction.
954 void copyArgsPassedByValToAllocas();
955
956 // Finds all Alloca instructions and puts
957 // poisoned red zones around all of them.
958 // Then unpoison everything back before the function returns.
959 void processStaticAllocas();
960 void processDynamicAllocas();
961
962 void createDynamicAllocasInitStorage();
963
964 // ----------------------- Visitors.
965 /// Collect all Ret instructions.
visitReturnInst__anond17fa1a10211::FunctionStackPoisoner966 void visitReturnInst(ReturnInst &RI) { RetVec.push_back(&RI); }
967
968 /// Collect all Resume instructions.
visitResumeInst__anond17fa1a10211::FunctionStackPoisoner969 void visitResumeInst(ResumeInst &RI) { RetVec.push_back(&RI); }
970
971 /// Collect all CatchReturnInst instructions.
visitCleanupReturnInst__anond17fa1a10211::FunctionStackPoisoner972 void visitCleanupReturnInst(CleanupReturnInst &CRI) { RetVec.push_back(&CRI); }
973
unpoisonDynamicAllocasBeforeInst__anond17fa1a10211::FunctionStackPoisoner974 void unpoisonDynamicAllocasBeforeInst(Instruction *InstBefore,
975 Value *SavedStack) {
976 IRBuilder<> IRB(InstBefore);
977 Value *DynamicAreaPtr = IRB.CreatePtrToInt(SavedStack, IntptrTy);
978 // When we insert _asan_allocas_unpoison before @llvm.stackrestore, we
979 // need to adjust extracted SP to compute the address of the most recent
980 // alloca. We have a special @llvm.get.dynamic.area.offset intrinsic for
981 // this purpose.
982 if (!isa<ReturnInst>(InstBefore)) {
983 Function *DynamicAreaOffsetFunc = Intrinsic::getDeclaration(
984 InstBefore->getModule(), Intrinsic::get_dynamic_area_offset,
985 {IntptrTy});
986
987 Value *DynamicAreaOffset = IRB.CreateCall(DynamicAreaOffsetFunc, {});
988
989 DynamicAreaPtr = IRB.CreateAdd(IRB.CreatePtrToInt(SavedStack, IntptrTy),
990 DynamicAreaOffset);
991 }
992
993 IRB.CreateCall(
994 AsanAllocasUnpoisonFunc,
995 {IRB.CreateLoad(IntptrTy, DynamicAllocaLayout), DynamicAreaPtr});
996 }
997
998 // Unpoison dynamic allocas redzones.
unpoisonDynamicAllocas__anond17fa1a10211::FunctionStackPoisoner999 void unpoisonDynamicAllocas() {
1000 for (auto &Ret : RetVec)
1001 unpoisonDynamicAllocasBeforeInst(Ret, DynamicAllocaLayout);
1002
1003 for (auto &StackRestoreInst : StackRestoreVec)
1004 unpoisonDynamicAllocasBeforeInst(StackRestoreInst,
1005 StackRestoreInst->getOperand(0));
1006 }
1007
1008 // Deploy and poison redzones around dynamic alloca call. To do this, we
1009 // should replace this call with another one with changed parameters and
1010 // replace all its uses with new address, so
1011 // addr = alloca type, old_size, align
1012 // is replaced by
1013 // new_size = (old_size + additional_size) * sizeof(type)
1014 // tmp = alloca i8, new_size, max(align, 32)
1015 // addr = tmp + 32 (first 32 bytes are for the left redzone).
1016 // Additional_size is added to make new memory allocation contain not only
1017 // requested memory, but also left, partial and right redzones.
1018 void handleDynamicAllocaCall(AllocaInst *AI);
1019
1020 /// Collect Alloca instructions we want (and can) handle.
visitAllocaInst__anond17fa1a10211::FunctionStackPoisoner1021 void visitAllocaInst(AllocaInst &AI) {
1022 if (!ASan.isInterestingAlloca(AI)) {
1023 if (AI.isStaticAlloca()) {
1024 // Skip over allocas that are present *before* the first instrumented
1025 // alloca, we don't want to move those around.
1026 if (AllocaVec.empty())
1027 return;
1028
1029 StaticAllocasToMoveUp.push_back(&AI);
1030 }
1031 return;
1032 }
1033
1034 StackAlignment = std::max(StackAlignment, AI.getAlignment());
1035 if (!AI.isStaticAlloca())
1036 DynamicAllocaVec.push_back(&AI);
1037 else
1038 AllocaVec.push_back(&AI);
1039 }
1040
1041 /// Collect lifetime intrinsic calls to check for use-after-scope
1042 /// errors.
visitIntrinsicInst__anond17fa1a10211::FunctionStackPoisoner1043 void visitIntrinsicInst(IntrinsicInst &II) {
1044 Intrinsic::ID ID = II.getIntrinsicID();
1045 if (ID == Intrinsic::stackrestore) StackRestoreVec.push_back(&II);
1046 if (ID == Intrinsic::localescape) LocalEscapeCall = &II;
1047 if (!ASan.UseAfterScope)
1048 return;
1049 if (!II.isLifetimeStartOrEnd())
1050 return;
1051 // Found lifetime intrinsic, add ASan instrumentation if necessary.
1052 auto *Size = cast<ConstantInt>(II.getArgOperand(0));
1053 // If size argument is undefined, don't do anything.
1054 if (Size->isMinusOne()) return;
1055 // Check that size doesn't saturate uint64_t and can
1056 // be stored in IntptrTy.
1057 const uint64_t SizeValue = Size->getValue().getLimitedValue();
1058 if (SizeValue == ~0ULL ||
1059 !ConstantInt::isValueValidForType(IntptrTy, SizeValue))
1060 return;
1061 // Find alloca instruction that corresponds to llvm.lifetime argument.
1062 AllocaInst *AI =
1063 llvm::findAllocaForValue(II.getArgOperand(1), AllocaForValue);
1064 if (!AI) {
1065 HasUntracedLifetimeIntrinsic = true;
1066 return;
1067 }
1068 // We're interested only in allocas we can handle.
1069 if (!ASan.isInterestingAlloca(*AI))
1070 return;
1071 bool DoPoison = (ID == Intrinsic::lifetime_end);
1072 AllocaPoisonCall APC = {&II, AI, SizeValue, DoPoison};
1073 if (AI->isStaticAlloca())
1074 StaticAllocaPoisonCallVec.push_back(APC);
1075 else if (ClInstrumentDynamicAllocas)
1076 DynamicAllocaPoisonCallVec.push_back(APC);
1077 }
1078
visitCallSite__anond17fa1a10211::FunctionStackPoisoner1079 void visitCallSite(CallSite CS) {
1080 Instruction *I = CS.getInstruction();
1081 if (CallInst *CI = dyn_cast<CallInst>(I)) {
1082 HasNonEmptyInlineAsm |= CI->isInlineAsm() &&
1083 !CI->isIdenticalTo(EmptyInlineAsm.get()) &&
1084 I != ASan.LocalDynamicShadow;
1085 HasReturnsTwiceCall |= CI->canReturnTwice();
1086 }
1087 }
1088
1089 // ---------------------- Helpers.
1090 void initializeCallbacks(Module &M);
1091
1092 // Copies bytes from ShadowBytes into shadow memory for indexes where
1093 // ShadowMask is not zero. If ShadowMask[i] is zero, we assume that
1094 // ShadowBytes[i] is constantly zero and doesn't need to be overwritten.
1095 void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
1096 IRBuilder<> &IRB, Value *ShadowBase);
1097 void copyToShadow(ArrayRef<uint8_t> ShadowMask, ArrayRef<uint8_t> ShadowBytes,
1098 size_t Begin, size_t End, IRBuilder<> &IRB,
1099 Value *ShadowBase);
1100 void copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
1101 ArrayRef<uint8_t> ShadowBytes, size_t Begin,
1102 size_t End, IRBuilder<> &IRB, Value *ShadowBase);
1103
1104 void poisonAlloca(Value *V, uint64_t Size, IRBuilder<> &IRB, bool DoPoison);
1105
1106 Value *createAllocaForLayout(IRBuilder<> &IRB, const ASanStackFrameLayout &L,
1107 bool Dynamic);
1108 PHINode *createPHI(IRBuilder<> &IRB, Value *Cond, Value *ValueIfTrue,
1109 Instruction *ThenTerm, Value *ValueIfFalse);
1110 };
1111
1112 } // end anonymous namespace
1113
parse(MDNode * MDN)1114 void LocationMetadata::parse(MDNode *MDN) {
1115 assert(MDN->getNumOperands() == 3);
1116 MDString *DIFilename = cast<MDString>(MDN->getOperand(0));
1117 Filename = DIFilename->getString();
1118 LineNo = mdconst::extract<ConstantInt>(MDN->getOperand(1))->getLimitedValue();
1119 ColumnNo =
1120 mdconst::extract<ConstantInt>(MDN->getOperand(2))->getLimitedValue();
1121 }
1122
1123 // FIXME: It would be cleaner to instead attach relevant metadata to the globals
1124 // we want to sanitize instead and reading this metadata on each pass over a
1125 // function instead of reading module level metadata at first.
GlobalsMetadata(Module & M)1126 GlobalsMetadata::GlobalsMetadata(Module &M) {
1127 NamedMDNode *Globals = M.getNamedMetadata("llvm.asan.globals");
1128 if (!Globals)
1129 return;
1130 for (auto MDN : Globals->operands()) {
1131 // Metadata node contains the global and the fields of "Entry".
1132 assert(MDN->getNumOperands() == 5);
1133 auto *V = mdconst::extract_or_null<Constant>(MDN->getOperand(0));
1134 // The optimizer may optimize away a global entirely.
1135 if (!V)
1136 continue;
1137 auto *StrippedV = V->stripPointerCasts();
1138 auto *GV = dyn_cast<GlobalVariable>(StrippedV);
1139 if (!GV)
1140 continue;
1141 // We can already have an entry for GV if it was merged with another
1142 // global.
1143 Entry &E = Entries[GV];
1144 if (auto *Loc = cast_or_null<MDNode>(MDN->getOperand(1)))
1145 E.SourceLoc.parse(Loc);
1146 if (auto *Name = cast_or_null<MDString>(MDN->getOperand(2)))
1147 E.Name = Name->getString();
1148 ConstantInt *IsDynInit = mdconst::extract<ConstantInt>(MDN->getOperand(3));
1149 E.IsDynInit |= IsDynInit->isOne();
1150 ConstantInt *IsBlacklisted =
1151 mdconst::extract<ConstantInt>(MDN->getOperand(4));
1152 E.IsBlacklisted |= IsBlacklisted->isOne();
1153 }
1154 }
1155
1156 AnalysisKey ASanGlobalsMetadataAnalysis::Key;
1157
run(Module & M,ModuleAnalysisManager & AM)1158 GlobalsMetadata ASanGlobalsMetadataAnalysis::run(Module &M,
1159 ModuleAnalysisManager &AM) {
1160 return GlobalsMetadata(M);
1161 }
1162
AddressSanitizerPass(bool CompileKernel,bool Recover,bool UseAfterScope)1163 AddressSanitizerPass::AddressSanitizerPass(bool CompileKernel, bool Recover,
1164 bool UseAfterScope)
1165 : CompileKernel(CompileKernel), Recover(Recover),
1166 UseAfterScope(UseAfterScope) {}
1167
run(Function & F,AnalysisManager<Function> & AM)1168 PreservedAnalyses AddressSanitizerPass::run(Function &F,
1169 AnalysisManager<Function> &AM) {
1170 auto &MAMProxy = AM.getResult<ModuleAnalysisManagerFunctionProxy>(F);
1171 auto &MAM = MAMProxy.getManager();
1172 Module &M = *F.getParent();
1173 if (auto *R = MAM.getCachedResult<ASanGlobalsMetadataAnalysis>(M)) {
1174 const TargetLibraryInfo *TLI = &AM.getResult<TargetLibraryAnalysis>(F);
1175 AddressSanitizer Sanitizer(M, R, CompileKernel, Recover, UseAfterScope);
1176 if (Sanitizer.instrumentFunction(F, TLI))
1177 return PreservedAnalyses::none();
1178 return PreservedAnalyses::all();
1179 }
1180
1181 report_fatal_error(
1182 "The ASanGlobalsMetadataAnalysis is required to run before "
1183 "AddressSanitizer can run");
1184 return PreservedAnalyses::all();
1185 }
1186
ModuleAddressSanitizerPass(bool CompileKernel,bool Recover,bool UseGlobalGC,bool UseOdrIndicator)1187 ModuleAddressSanitizerPass::ModuleAddressSanitizerPass(bool CompileKernel,
1188 bool Recover,
1189 bool UseGlobalGC,
1190 bool UseOdrIndicator)
1191 : CompileKernel(CompileKernel), Recover(Recover), UseGlobalGC(UseGlobalGC),
1192 UseOdrIndicator(UseOdrIndicator) {}
1193
run(Module & M,AnalysisManager<Module> & AM)1194 PreservedAnalyses ModuleAddressSanitizerPass::run(Module &M,
1195 AnalysisManager<Module> &AM) {
1196 GlobalsMetadata &GlobalsMD = AM.getResult<ASanGlobalsMetadataAnalysis>(M);
1197 ModuleAddressSanitizer Sanitizer(M, &GlobalsMD, CompileKernel, Recover,
1198 UseGlobalGC, UseOdrIndicator);
1199 if (Sanitizer.instrumentModule(M))
1200 return PreservedAnalyses::none();
1201 return PreservedAnalyses::all();
1202 }
1203
1204 INITIALIZE_PASS(ASanGlobalsMetadataWrapperPass, "asan-globals-md",
1205 "Read metadata to mark which globals should be instrumented "
1206 "when running ASan.",
1207 false, true)
1208
1209 char AddressSanitizerLegacyPass::ID = 0;
1210
1211 INITIALIZE_PASS_BEGIN(
1212 AddressSanitizerLegacyPass, "asan",
1213 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
1214 false)
INITIALIZE_PASS_DEPENDENCY(ASanGlobalsMetadataWrapperPass)1215 INITIALIZE_PASS_DEPENDENCY(ASanGlobalsMetadataWrapperPass)
1216 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
1217 INITIALIZE_PASS_END(
1218 AddressSanitizerLegacyPass, "asan",
1219 "AddressSanitizer: detects use-after-free and out-of-bounds bugs.", false,
1220 false)
1221
1222 FunctionPass *llvm::createAddressSanitizerFunctionPass(bool CompileKernel,
1223 bool Recover,
1224 bool UseAfterScope) {
1225 assert(!CompileKernel || Recover);
1226 return new AddressSanitizerLegacyPass(CompileKernel, Recover, UseAfterScope);
1227 }
1228
1229 char ModuleAddressSanitizerLegacyPass::ID = 0;
1230
1231 INITIALIZE_PASS(
1232 ModuleAddressSanitizerLegacyPass, "asan-module",
1233 "AddressSanitizer: detects use-after-free and out-of-bounds bugs."
1234 "ModulePass",
1235 false, false)
1236
createModuleAddressSanitizerLegacyPassPass(bool CompileKernel,bool Recover,bool UseGlobalsGC,bool UseOdrIndicator)1237 ModulePass *llvm::createModuleAddressSanitizerLegacyPassPass(
1238 bool CompileKernel, bool Recover, bool UseGlobalsGC, bool UseOdrIndicator) {
1239 assert(!CompileKernel || Recover);
1240 return new ModuleAddressSanitizerLegacyPass(CompileKernel, Recover,
1241 UseGlobalsGC, UseOdrIndicator);
1242 }
1243
TypeSizeToSizeIndex(uint32_t TypeSize)1244 static size_t TypeSizeToSizeIndex(uint32_t TypeSize) {
1245 size_t Res = countTrailingZeros(TypeSize / 8);
1246 assert(Res < kNumberOfAccessSizes);
1247 return Res;
1248 }
1249
1250 /// Create a global describing a source location.
createPrivateGlobalForSourceLoc(Module & M,LocationMetadata MD)1251 static GlobalVariable *createPrivateGlobalForSourceLoc(Module &M,
1252 LocationMetadata MD) {
1253 Constant *LocData[] = {
1254 createPrivateGlobalForString(M, MD.Filename, true, kAsanGenPrefix),
1255 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.LineNo),
1256 ConstantInt::get(Type::getInt32Ty(M.getContext()), MD.ColumnNo),
1257 };
1258 auto LocStruct = ConstantStruct::getAnon(LocData);
1259 auto GV = new GlobalVariable(M, LocStruct->getType(), true,
1260 GlobalValue::PrivateLinkage, LocStruct,
1261 kAsanGenPrefix);
1262 GV->setUnnamedAddr(GlobalValue::UnnamedAddr::Global);
1263 return GV;
1264 }
1265
1266 /// Check if \p G has been created by a trusted compiler pass.
GlobalWasGeneratedByCompiler(GlobalVariable * G)1267 static bool GlobalWasGeneratedByCompiler(GlobalVariable *G) {
1268 // Do not instrument @llvm.global_ctors, @llvm.used, etc.
1269 if (G->getName().startswith("llvm."))
1270 return true;
1271
1272 // Do not instrument asan globals.
1273 if (G->getName().startswith(kAsanGenPrefix) ||
1274 G->getName().startswith(kSanCovGenPrefix) ||
1275 G->getName().startswith(kODRGenPrefix))
1276 return true;
1277
1278 // Do not instrument gcov counter arrays.
1279 if (G->getName() == "__llvm_gcov_ctr")
1280 return true;
1281
1282 return false;
1283 }
1284
memToShadow(Value * Shadow,IRBuilder<> & IRB)1285 Value *AddressSanitizer::memToShadow(Value *Shadow, IRBuilder<> &IRB) {
1286 // Shadow >> scale
1287 Shadow = IRB.CreateLShr(Shadow, Mapping.Scale);
1288 if (Mapping.Offset == 0) return Shadow;
1289 // (Shadow >> scale) | offset
1290 Value *ShadowBase;
1291 if (LocalDynamicShadow)
1292 ShadowBase = LocalDynamicShadow;
1293 else
1294 ShadowBase = ConstantInt::get(IntptrTy, Mapping.Offset);
1295 if (Mapping.OrShadowOffset)
1296 return IRB.CreateOr(Shadow, ShadowBase);
1297 else
1298 return IRB.CreateAdd(Shadow, ShadowBase);
1299 }
1300
1301 // Instrument memset/memmove/memcpy
instrumentMemIntrinsic(MemIntrinsic * MI)1302 void AddressSanitizer::instrumentMemIntrinsic(MemIntrinsic *MI) {
1303 IRBuilder<> IRB(MI);
1304 if (isa<MemTransferInst>(MI)) {
1305 IRB.CreateCall(
1306 isa<MemMoveInst>(MI) ? AsanMemmove : AsanMemcpy,
1307 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
1308 IRB.CreatePointerCast(MI->getOperand(1), IRB.getInt8PtrTy()),
1309 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
1310 } else if (isa<MemSetInst>(MI)) {
1311 IRB.CreateCall(
1312 AsanMemset,
1313 {IRB.CreatePointerCast(MI->getOperand(0), IRB.getInt8PtrTy()),
1314 IRB.CreateIntCast(MI->getOperand(1), IRB.getInt32Ty(), false),
1315 IRB.CreateIntCast(MI->getOperand(2), IntptrTy, false)});
1316 }
1317 MI->eraseFromParent();
1318 }
1319
1320 /// Check if we want (and can) handle this alloca.
isInterestingAlloca(const AllocaInst & AI)1321 bool AddressSanitizer::isInterestingAlloca(const AllocaInst &AI) {
1322 auto PreviouslySeenAllocaInfo = ProcessedAllocas.find(&AI);
1323
1324 if (PreviouslySeenAllocaInfo != ProcessedAllocas.end())
1325 return PreviouslySeenAllocaInfo->getSecond();
1326
1327 bool IsInteresting =
1328 (AI.getAllocatedType()->isSized() &&
1329 // alloca() may be called with 0 size, ignore it.
1330 ((!AI.isStaticAlloca()) || getAllocaSizeInBytes(AI) > 0) &&
1331 // We are only interested in allocas not promotable to registers.
1332 // Promotable allocas are common under -O0.
1333 (!ClSkipPromotableAllocas || !isAllocaPromotable(&AI)) &&
1334 // inalloca allocas are not treated as static, and we don't want
1335 // dynamic alloca instrumentation for them as well.
1336 !AI.isUsedWithInAlloca() &&
1337 // swifterror allocas are register promoted by ISel
1338 !AI.isSwiftError());
1339
1340 ProcessedAllocas[&AI] = IsInteresting;
1341 return IsInteresting;
1342 }
1343
isInterestingMemoryAccess(Instruction * I,bool * IsWrite,uint64_t * TypeSize,unsigned * Alignment,Value ** MaybeMask)1344 Value *AddressSanitizer::isInterestingMemoryAccess(Instruction *I,
1345 bool *IsWrite,
1346 uint64_t *TypeSize,
1347 unsigned *Alignment,
1348 Value **MaybeMask) {
1349 // Skip memory accesses inserted by another instrumentation.
1350 if (I->hasMetadata("nosanitize")) return nullptr;
1351
1352 // Do not instrument the load fetching the dynamic shadow address.
1353 if (LocalDynamicShadow == I)
1354 return nullptr;
1355
1356 Value *PtrOperand = nullptr;
1357 const DataLayout &DL = I->getModule()->getDataLayout();
1358 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
1359 if (!ClInstrumentReads) return nullptr;
1360 *IsWrite = false;
1361 *TypeSize = DL.getTypeStoreSizeInBits(LI->getType());
1362 *Alignment = LI->getAlignment();
1363 PtrOperand = LI->getPointerOperand();
1364 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
1365 if (!ClInstrumentWrites) return nullptr;
1366 *IsWrite = true;
1367 *TypeSize = DL.getTypeStoreSizeInBits(SI->getValueOperand()->getType());
1368 *Alignment = SI->getAlignment();
1369 PtrOperand = SI->getPointerOperand();
1370 } else if (AtomicRMWInst *RMW = dyn_cast<AtomicRMWInst>(I)) {
1371 if (!ClInstrumentAtomics) return nullptr;
1372 *IsWrite = true;
1373 *TypeSize = DL.getTypeStoreSizeInBits(RMW->getValOperand()->getType());
1374 *Alignment = 0;
1375 PtrOperand = RMW->getPointerOperand();
1376 } else if (AtomicCmpXchgInst *XCHG = dyn_cast<AtomicCmpXchgInst>(I)) {
1377 if (!ClInstrumentAtomics) return nullptr;
1378 *IsWrite = true;
1379 *TypeSize = DL.getTypeStoreSizeInBits(XCHG->getCompareOperand()->getType());
1380 *Alignment = 0;
1381 PtrOperand = XCHG->getPointerOperand();
1382 } else if (auto CI = dyn_cast<CallInst>(I)) {
1383 auto *F = dyn_cast<Function>(CI->getCalledValue());
1384 if (F && (F->getName().startswith("llvm.masked.load.") ||
1385 F->getName().startswith("llvm.masked.store."))) {
1386 unsigned OpOffset = 0;
1387 if (F->getName().startswith("llvm.masked.store.")) {
1388 if (!ClInstrumentWrites)
1389 return nullptr;
1390 // Masked store has an initial operand for the value.
1391 OpOffset = 1;
1392 *IsWrite = true;
1393 } else {
1394 if (!ClInstrumentReads)
1395 return nullptr;
1396 *IsWrite = false;
1397 }
1398
1399 auto BasePtr = CI->getOperand(0 + OpOffset);
1400 auto Ty = cast<PointerType>(BasePtr->getType())->getElementType();
1401 *TypeSize = DL.getTypeStoreSizeInBits(Ty);
1402 if (auto AlignmentConstant =
1403 dyn_cast<ConstantInt>(CI->getOperand(1 + OpOffset)))
1404 *Alignment = (unsigned)AlignmentConstant->getZExtValue();
1405 else
1406 *Alignment = 1; // No alignment guarantees. We probably got Undef
1407 if (MaybeMask)
1408 *MaybeMask = CI->getOperand(2 + OpOffset);
1409 PtrOperand = BasePtr;
1410 }
1411 }
1412
1413 if (PtrOperand) {
1414 // Do not instrument acesses from different address spaces; we cannot deal
1415 // with them.
1416 Type *PtrTy = cast<PointerType>(PtrOperand->getType()->getScalarType());
1417 if (PtrTy->getPointerAddressSpace() != 0)
1418 return nullptr;
1419
1420 // Ignore swifterror addresses.
1421 // swifterror memory addresses are mem2reg promoted by instruction
1422 // selection. As such they cannot have regular uses like an instrumentation
1423 // function and it makes no sense to track them as memory.
1424 if (PtrOperand->isSwiftError())
1425 return nullptr;
1426 }
1427
1428 // Treat memory accesses to promotable allocas as non-interesting since they
1429 // will not cause memory violations. This greatly speeds up the instrumented
1430 // executable at -O0.
1431 if (ClSkipPromotableAllocas)
1432 if (auto AI = dyn_cast_or_null<AllocaInst>(PtrOperand))
1433 return isInterestingAlloca(*AI) ? AI : nullptr;
1434
1435 return PtrOperand;
1436 }
1437
isPointerOperand(Value * V)1438 static bool isPointerOperand(Value *V) {
1439 return V->getType()->isPointerTy() || isa<PtrToIntInst>(V);
1440 }
1441
1442 // This is a rough heuristic; it may cause both false positives and
1443 // false negatives. The proper implementation requires cooperation with
1444 // the frontend.
isInterestingPointerComparison(Instruction * I)1445 static bool isInterestingPointerComparison(Instruction *I) {
1446 if (ICmpInst *Cmp = dyn_cast<ICmpInst>(I)) {
1447 if (!Cmp->isRelational())
1448 return false;
1449 } else {
1450 return false;
1451 }
1452 return isPointerOperand(I->getOperand(0)) &&
1453 isPointerOperand(I->getOperand(1));
1454 }
1455
1456 // This is a rough heuristic; it may cause both false positives and
1457 // false negatives. The proper implementation requires cooperation with
1458 // the frontend.
isInterestingPointerSubtraction(Instruction * I)1459 static bool isInterestingPointerSubtraction(Instruction *I) {
1460 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
1461 if (BO->getOpcode() != Instruction::Sub)
1462 return false;
1463 } else {
1464 return false;
1465 }
1466 return isPointerOperand(I->getOperand(0)) &&
1467 isPointerOperand(I->getOperand(1));
1468 }
1469
GlobalIsLinkerInitialized(GlobalVariable * G)1470 bool AddressSanitizer::GlobalIsLinkerInitialized(GlobalVariable *G) {
1471 // If a global variable does not have dynamic initialization we don't
1472 // have to instrument it. However, if a global does not have initializer
1473 // at all, we assume it has dynamic initializer (in other TU).
1474 //
1475 // FIXME: Metadata should be attched directly to the global directly instead
1476 // of being added to llvm.asan.globals.
1477 return G->hasInitializer() && !GlobalsMD.get(G).IsDynInit;
1478 }
1479
instrumentPointerComparisonOrSubtraction(Instruction * I)1480 void AddressSanitizer::instrumentPointerComparisonOrSubtraction(
1481 Instruction *I) {
1482 IRBuilder<> IRB(I);
1483 FunctionCallee F = isa<ICmpInst>(I) ? AsanPtrCmpFunction : AsanPtrSubFunction;
1484 Value *Param[2] = {I->getOperand(0), I->getOperand(1)};
1485 for (Value *&i : Param) {
1486 if (i->getType()->isPointerTy())
1487 i = IRB.CreatePointerCast(i, IntptrTy);
1488 }
1489 IRB.CreateCall(F, Param);
1490 }
1491
doInstrumentAddress(AddressSanitizer * Pass,Instruction * I,Instruction * InsertBefore,Value * Addr,unsigned Alignment,unsigned Granularity,uint32_t TypeSize,bool IsWrite,Value * SizeArgument,bool UseCalls,uint32_t Exp)1492 static void doInstrumentAddress(AddressSanitizer *Pass, Instruction *I,
1493 Instruction *InsertBefore, Value *Addr,
1494 unsigned Alignment, unsigned Granularity,
1495 uint32_t TypeSize, bool IsWrite,
1496 Value *SizeArgument, bool UseCalls,
1497 uint32_t Exp) {
1498 // Instrument a 1-, 2-, 4-, 8-, or 16- byte access with one check
1499 // if the data is properly aligned.
1500 if ((TypeSize == 8 || TypeSize == 16 || TypeSize == 32 || TypeSize == 64 ||
1501 TypeSize == 128) &&
1502 (Alignment >= Granularity || Alignment == 0 || Alignment >= TypeSize / 8))
1503 return Pass->instrumentAddress(I, InsertBefore, Addr, TypeSize, IsWrite,
1504 nullptr, UseCalls, Exp);
1505 Pass->instrumentUnusualSizeOrAlignment(I, InsertBefore, Addr, TypeSize,
1506 IsWrite, nullptr, UseCalls, Exp);
1507 }
1508
instrumentMaskedLoadOrStore(AddressSanitizer * Pass,const DataLayout & DL,Type * IntptrTy,Value * Mask,Instruction * I,Value * Addr,unsigned Alignment,unsigned Granularity,uint32_t TypeSize,bool IsWrite,Value * SizeArgument,bool UseCalls,uint32_t Exp)1509 static void instrumentMaskedLoadOrStore(AddressSanitizer *Pass,
1510 const DataLayout &DL, Type *IntptrTy,
1511 Value *Mask, Instruction *I,
1512 Value *Addr, unsigned Alignment,
1513 unsigned Granularity, uint32_t TypeSize,
1514 bool IsWrite, Value *SizeArgument,
1515 bool UseCalls, uint32_t Exp) {
1516 auto *VTy = cast<PointerType>(Addr->getType())->getElementType();
1517 uint64_t ElemTypeSize = DL.getTypeStoreSizeInBits(VTy->getScalarType());
1518 unsigned Num = VTy->getVectorNumElements();
1519 auto Zero = ConstantInt::get(IntptrTy, 0);
1520 for (unsigned Idx = 0; Idx < Num; ++Idx) {
1521 Value *InstrumentedAddress = nullptr;
1522 Instruction *InsertBefore = I;
1523 if (auto *Vector = dyn_cast<ConstantVector>(Mask)) {
1524 // dyn_cast as we might get UndefValue
1525 if (auto *Masked = dyn_cast<ConstantInt>(Vector->getOperand(Idx))) {
1526 if (Masked->isZero())
1527 // Mask is constant false, so no instrumentation needed.
1528 continue;
1529 // If we have a true or undef value, fall through to doInstrumentAddress
1530 // with InsertBefore == I
1531 }
1532 } else {
1533 IRBuilder<> IRB(I);
1534 Value *MaskElem = IRB.CreateExtractElement(Mask, Idx);
1535 Instruction *ThenTerm = SplitBlockAndInsertIfThen(MaskElem, I, false);
1536 InsertBefore = ThenTerm;
1537 }
1538
1539 IRBuilder<> IRB(InsertBefore);
1540 InstrumentedAddress =
1541 IRB.CreateGEP(VTy, Addr, {Zero, ConstantInt::get(IntptrTy, Idx)});
1542 doInstrumentAddress(Pass, I, InsertBefore, InstrumentedAddress, Alignment,
1543 Granularity, ElemTypeSize, IsWrite, SizeArgument,
1544 UseCalls, Exp);
1545 }
1546 }
1547
instrumentMop(ObjectSizeOffsetVisitor & ObjSizeVis,Instruction * I,bool UseCalls,const DataLayout & DL)1548 void AddressSanitizer::instrumentMop(ObjectSizeOffsetVisitor &ObjSizeVis,
1549 Instruction *I, bool UseCalls,
1550 const DataLayout &DL) {
1551 bool IsWrite = false;
1552 unsigned Alignment = 0;
1553 uint64_t TypeSize = 0;
1554 Value *MaybeMask = nullptr;
1555 Value *Addr =
1556 isInterestingMemoryAccess(I, &IsWrite, &TypeSize, &Alignment, &MaybeMask);
1557 assert(Addr);
1558
1559 // Optimization experiments.
1560 // The experiments can be used to evaluate potential optimizations that remove
1561 // instrumentation (assess false negatives). Instead of completely removing
1562 // some instrumentation, you set Exp to a non-zero value (mask of optimization
1563 // experiments that want to remove instrumentation of this instruction).
1564 // If Exp is non-zero, this pass will emit special calls into runtime
1565 // (e.g. __asan_report_exp_load1 instead of __asan_report_load1). These calls
1566 // make runtime terminate the program in a special way (with a different
1567 // exit status). Then you run the new compiler on a buggy corpus, collect
1568 // the special terminations (ideally, you don't see them at all -- no false
1569 // negatives) and make the decision on the optimization.
1570 uint32_t Exp = ClForceExperiment;
1571
1572 if (ClOpt && ClOptGlobals) {
1573 // If initialization order checking is disabled, a simple access to a
1574 // dynamically initialized global is always valid.
1575 GlobalVariable *G = dyn_cast<GlobalVariable>(GetUnderlyingObject(Addr, DL));
1576 if (G && (!ClInitializers || GlobalIsLinkerInitialized(G)) &&
1577 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
1578 NumOptimizedAccessesToGlobalVar++;
1579 return;
1580 }
1581 }
1582
1583 if (ClOpt && ClOptStack) {
1584 // A direct inbounds access to a stack variable is always valid.
1585 if (isa<AllocaInst>(GetUnderlyingObject(Addr, DL)) &&
1586 isSafeAccess(ObjSizeVis, Addr, TypeSize)) {
1587 NumOptimizedAccessesToStackVar++;
1588 return;
1589 }
1590 }
1591
1592 if (IsWrite)
1593 NumInstrumentedWrites++;
1594 else
1595 NumInstrumentedReads++;
1596
1597 unsigned Granularity = 1 << Mapping.Scale;
1598 if (MaybeMask) {
1599 instrumentMaskedLoadOrStore(this, DL, IntptrTy, MaybeMask, I, Addr,
1600 Alignment, Granularity, TypeSize, IsWrite,
1601 nullptr, UseCalls, Exp);
1602 } else {
1603 doInstrumentAddress(this, I, I, Addr, Alignment, Granularity, TypeSize,
1604 IsWrite, nullptr, UseCalls, Exp);
1605 }
1606 }
1607
generateCrashCode(Instruction * InsertBefore,Value * Addr,bool IsWrite,size_t AccessSizeIndex,Value * SizeArgument,uint32_t Exp)1608 Instruction *AddressSanitizer::generateCrashCode(Instruction *InsertBefore,
1609 Value *Addr, bool IsWrite,
1610 size_t AccessSizeIndex,
1611 Value *SizeArgument,
1612 uint32_t Exp) {
1613 IRBuilder<> IRB(InsertBefore);
1614 Value *ExpVal = Exp == 0 ? nullptr : ConstantInt::get(IRB.getInt32Ty(), Exp);
1615 CallInst *Call = nullptr;
1616 if (SizeArgument) {
1617 if (Exp == 0)
1618 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][0],
1619 {Addr, SizeArgument});
1620 else
1621 Call = IRB.CreateCall(AsanErrorCallbackSized[IsWrite][1],
1622 {Addr, SizeArgument, ExpVal});
1623 } else {
1624 if (Exp == 0)
1625 Call =
1626 IRB.CreateCall(AsanErrorCallback[IsWrite][0][AccessSizeIndex], Addr);
1627 else
1628 Call = IRB.CreateCall(AsanErrorCallback[IsWrite][1][AccessSizeIndex],
1629 {Addr, ExpVal});
1630 }
1631
1632 // We don't do Call->setDoesNotReturn() because the BB already has
1633 // UnreachableInst at the end.
1634 // This EmptyAsm is required to avoid callback merge.
1635 IRB.CreateCall(EmptyAsm, {});
1636 return Call;
1637 }
1638
createSlowPathCmp(IRBuilder<> & IRB,Value * AddrLong,Value * ShadowValue,uint32_t TypeSize)1639 Value *AddressSanitizer::createSlowPathCmp(IRBuilder<> &IRB, Value *AddrLong,
1640 Value *ShadowValue,
1641 uint32_t TypeSize) {
1642 size_t Granularity = static_cast<size_t>(1) << Mapping.Scale;
1643 // Addr & (Granularity - 1)
1644 Value *LastAccessedByte =
1645 IRB.CreateAnd(AddrLong, ConstantInt::get(IntptrTy, Granularity - 1));
1646 // (Addr & (Granularity - 1)) + size - 1
1647 if (TypeSize / 8 > 1)
1648 LastAccessedByte = IRB.CreateAdd(
1649 LastAccessedByte, ConstantInt::get(IntptrTy, TypeSize / 8 - 1));
1650 // (uint8_t) ((Addr & (Granularity-1)) + size - 1)
1651 LastAccessedByte =
1652 IRB.CreateIntCast(LastAccessedByte, ShadowValue->getType(), false);
1653 // ((uint8_t) ((Addr & (Granularity-1)) + size - 1)) >= ShadowValue
1654 return IRB.CreateICmpSGE(LastAccessedByte, ShadowValue);
1655 }
1656
instrumentAddress(Instruction * OrigIns,Instruction * InsertBefore,Value * Addr,uint32_t TypeSize,bool IsWrite,Value * SizeArgument,bool UseCalls,uint32_t Exp)1657 void AddressSanitizer::instrumentAddress(Instruction *OrigIns,
1658 Instruction *InsertBefore, Value *Addr,
1659 uint32_t TypeSize, bool IsWrite,
1660 Value *SizeArgument, bool UseCalls,
1661 uint32_t Exp) {
1662 bool IsMyriad = TargetTriple.getVendor() == llvm::Triple::Myriad;
1663
1664 IRBuilder<> IRB(InsertBefore);
1665 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1666 size_t AccessSizeIndex = TypeSizeToSizeIndex(TypeSize);
1667
1668 if (UseCalls) {
1669 if (Exp == 0)
1670 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][0][AccessSizeIndex],
1671 AddrLong);
1672 else
1673 IRB.CreateCall(AsanMemoryAccessCallback[IsWrite][1][AccessSizeIndex],
1674 {AddrLong, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1675 return;
1676 }
1677
1678 if (IsMyriad) {
1679 // Strip the cache bit and do range check.
1680 // AddrLong &= ~kMyriadCacheBitMask32
1681 AddrLong = IRB.CreateAnd(AddrLong, ~kMyriadCacheBitMask32);
1682 // Tag = AddrLong >> kMyriadTagShift
1683 Value *Tag = IRB.CreateLShr(AddrLong, kMyriadTagShift);
1684 // Tag == kMyriadDDRTag
1685 Value *TagCheck =
1686 IRB.CreateICmpEQ(Tag, ConstantInt::get(IntptrTy, kMyriadDDRTag));
1687
1688 Instruction *TagCheckTerm =
1689 SplitBlockAndInsertIfThen(TagCheck, InsertBefore, false,
1690 MDBuilder(*C).createBranchWeights(1, 100000));
1691 assert(cast<BranchInst>(TagCheckTerm)->isUnconditional());
1692 IRB.SetInsertPoint(TagCheckTerm);
1693 InsertBefore = TagCheckTerm;
1694 }
1695
1696 Type *ShadowTy =
1697 IntegerType::get(*C, std::max(8U, TypeSize >> Mapping.Scale));
1698 Type *ShadowPtrTy = PointerType::get(ShadowTy, 0);
1699 Value *ShadowPtr = memToShadow(AddrLong, IRB);
1700 Value *CmpVal = Constant::getNullValue(ShadowTy);
1701 Value *ShadowValue =
1702 IRB.CreateLoad(ShadowTy, IRB.CreateIntToPtr(ShadowPtr, ShadowPtrTy));
1703
1704 Value *Cmp = IRB.CreateICmpNE(ShadowValue, CmpVal);
1705 size_t Granularity = 1ULL << Mapping.Scale;
1706 Instruction *CrashTerm = nullptr;
1707
1708 if (ClAlwaysSlowPath || (TypeSize < 8 * Granularity)) {
1709 // We use branch weights for the slow path check, to indicate that the slow
1710 // path is rarely taken. This seems to be the case for SPEC benchmarks.
1711 Instruction *CheckTerm = SplitBlockAndInsertIfThen(
1712 Cmp, InsertBefore, false, MDBuilder(*C).createBranchWeights(1, 100000));
1713 assert(cast<BranchInst>(CheckTerm)->isUnconditional());
1714 BasicBlock *NextBB = CheckTerm->getSuccessor(0);
1715 IRB.SetInsertPoint(CheckTerm);
1716 Value *Cmp2 = createSlowPathCmp(IRB, AddrLong, ShadowValue, TypeSize);
1717 if (Recover) {
1718 CrashTerm = SplitBlockAndInsertIfThen(Cmp2, CheckTerm, false);
1719 } else {
1720 BasicBlock *CrashBlock =
1721 BasicBlock::Create(*C, "", NextBB->getParent(), NextBB);
1722 CrashTerm = new UnreachableInst(*C, CrashBlock);
1723 BranchInst *NewTerm = BranchInst::Create(CrashBlock, NextBB, Cmp2);
1724 ReplaceInstWithInst(CheckTerm, NewTerm);
1725 }
1726 } else {
1727 CrashTerm = SplitBlockAndInsertIfThen(Cmp, InsertBefore, !Recover);
1728 }
1729
1730 Instruction *Crash = generateCrashCode(CrashTerm, AddrLong, IsWrite,
1731 AccessSizeIndex, SizeArgument, Exp);
1732 Crash->setDebugLoc(OrigIns->getDebugLoc());
1733 }
1734
1735 // Instrument unusual size or unusual alignment.
1736 // We can not do it with a single check, so we do 1-byte check for the first
1737 // and the last bytes. We call __asan_report_*_n(addr, real_size) to be able
1738 // to report the actual access size.
instrumentUnusualSizeOrAlignment(Instruction * I,Instruction * InsertBefore,Value * Addr,uint32_t TypeSize,bool IsWrite,Value * SizeArgument,bool UseCalls,uint32_t Exp)1739 void AddressSanitizer::instrumentUnusualSizeOrAlignment(
1740 Instruction *I, Instruction *InsertBefore, Value *Addr, uint32_t TypeSize,
1741 bool IsWrite, Value *SizeArgument, bool UseCalls, uint32_t Exp) {
1742 IRBuilder<> IRB(InsertBefore);
1743 Value *Size = ConstantInt::get(IntptrTy, TypeSize / 8);
1744 Value *AddrLong = IRB.CreatePointerCast(Addr, IntptrTy);
1745 if (UseCalls) {
1746 if (Exp == 0)
1747 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][0],
1748 {AddrLong, Size});
1749 else
1750 IRB.CreateCall(AsanMemoryAccessCallbackSized[IsWrite][1],
1751 {AddrLong, Size, ConstantInt::get(IRB.getInt32Ty(), Exp)});
1752 } else {
1753 Value *LastByte = IRB.CreateIntToPtr(
1754 IRB.CreateAdd(AddrLong, ConstantInt::get(IntptrTy, TypeSize / 8 - 1)),
1755 Addr->getType());
1756 instrumentAddress(I, InsertBefore, Addr, 8, IsWrite, Size, false, Exp);
1757 instrumentAddress(I, InsertBefore, LastByte, 8, IsWrite, Size, false, Exp);
1758 }
1759 }
1760
poisonOneInitializer(Function & GlobalInit,GlobalValue * ModuleName)1761 void ModuleAddressSanitizer::poisonOneInitializer(Function &GlobalInit,
1762 GlobalValue *ModuleName) {
1763 // Set up the arguments to our poison/unpoison functions.
1764 IRBuilder<> IRB(&GlobalInit.front(),
1765 GlobalInit.front().getFirstInsertionPt());
1766
1767 // Add a call to poison all external globals before the given function starts.
1768 Value *ModuleNameAddr = ConstantExpr::getPointerCast(ModuleName, IntptrTy);
1769 IRB.CreateCall(AsanPoisonGlobals, ModuleNameAddr);
1770
1771 // Add calls to unpoison all globals before each return instruction.
1772 for (auto &BB : GlobalInit.getBasicBlockList())
1773 if (ReturnInst *RI = dyn_cast<ReturnInst>(BB.getTerminator()))
1774 CallInst::Create(AsanUnpoisonGlobals, "", RI);
1775 }
1776
createInitializerPoisonCalls(Module & M,GlobalValue * ModuleName)1777 void ModuleAddressSanitizer::createInitializerPoisonCalls(
1778 Module &M, GlobalValue *ModuleName) {
1779 GlobalVariable *GV = M.getGlobalVariable("llvm.global_ctors");
1780 if (!GV)
1781 return;
1782
1783 ConstantArray *CA = dyn_cast<ConstantArray>(GV->getInitializer());
1784 if (!CA)
1785 return;
1786
1787 for (Use &OP : CA->operands()) {
1788 if (isa<ConstantAggregateZero>(OP)) continue;
1789 ConstantStruct *CS = cast<ConstantStruct>(OP);
1790
1791 // Must have a function or null ptr.
1792 if (Function *F = dyn_cast<Function>(CS->getOperand(1))) {
1793 if (F->getName() == kAsanModuleCtorName) continue;
1794 auto *Priority = cast<ConstantInt>(CS->getOperand(0));
1795 // Don't instrument CTORs that will run before asan.module_ctor.
1796 if (Priority->getLimitedValue() <= GetCtorAndDtorPriority(TargetTriple))
1797 continue;
1798 poisonOneInitializer(*F, ModuleName);
1799 }
1800 }
1801 }
1802
ShouldInstrumentGlobal(GlobalVariable * G)1803 bool ModuleAddressSanitizer::ShouldInstrumentGlobal(GlobalVariable *G) {
1804 Type *Ty = G->getValueType();
1805 LLVM_DEBUG(dbgs() << "GLOBAL: " << *G << "\n");
1806
1807 // FIXME: Metadata should be attched directly to the global directly instead
1808 // of being added to llvm.asan.globals.
1809 if (GlobalsMD.get(G).IsBlacklisted) return false;
1810 if (!Ty->isSized()) return false;
1811 if (!G->hasInitializer()) return false;
1812 // Only instrument globals of default address spaces
1813 if (G->getAddressSpace()) return false;
1814 if (GlobalWasGeneratedByCompiler(G)) return false; // Our own globals.
1815 // Two problems with thread-locals:
1816 // - The address of the main thread's copy can't be computed at link-time.
1817 // - Need to poison all copies, not just the main thread's one.
1818 if (G->isThreadLocal()) return false;
1819 // For now, just ignore this Global if the alignment is large.
1820 if (G->getAlignment() > MinRedzoneSizeForGlobal()) return false;
1821
1822 // For non-COFF targets, only instrument globals known to be defined by this
1823 // TU.
1824 // FIXME: We can instrument comdat globals on ELF if we are using the
1825 // GC-friendly metadata scheme.
1826 if (!TargetTriple.isOSBinFormatCOFF()) {
1827 if (!G->hasExactDefinition() || G->hasComdat())
1828 return false;
1829 } else {
1830 // On COFF, don't instrument non-ODR linkages.
1831 if (G->isInterposable())
1832 return false;
1833 }
1834
1835 // If a comdat is present, it must have a selection kind that implies ODR
1836 // semantics: no duplicates, any, or exact match.
1837 if (Comdat *C = G->getComdat()) {
1838 switch (C->getSelectionKind()) {
1839 case Comdat::Any:
1840 case Comdat::ExactMatch:
1841 case Comdat::NoDuplicates:
1842 break;
1843 case Comdat::Largest:
1844 case Comdat::SameSize:
1845 return false;
1846 }
1847 }
1848
1849 if (G->hasSection()) {
1850 StringRef Section = G->getSection();
1851
1852 // Globals from llvm.metadata aren't emitted, do not instrument them.
1853 if (Section == "llvm.metadata") return false;
1854 // Do not instrument globals from special LLVM sections.
1855 if (Section.find("__llvm") != StringRef::npos || Section.find("__LLVM") != StringRef::npos) return false;
1856
1857 // Do not instrument function pointers to initialization and termination
1858 // routines: dynamic linker will not properly handle redzones.
1859 if (Section.startswith(".preinit_array") ||
1860 Section.startswith(".init_array") ||
1861 Section.startswith(".fini_array")) {
1862 return false;
1863 }
1864
1865 // On COFF, if the section name contains '$', it is highly likely that the
1866 // user is using section sorting to create an array of globals similar to
1867 // the way initialization callbacks are registered in .init_array and
1868 // .CRT$XCU. The ATL also registers things in .ATL$__[azm]. Adding redzones
1869 // to such globals is counterproductive, because the intent is that they
1870 // will form an array, and out-of-bounds accesses are expected.
1871 // See https://github.com/google/sanitizers/issues/305
1872 // and http://msdn.microsoft.com/en-US/en-en/library/bb918180(v=vs.120).aspx
1873 if (TargetTriple.isOSBinFormatCOFF() && Section.contains('$')) {
1874 LLVM_DEBUG(dbgs() << "Ignoring global in sorted section (contains '$'): "
1875 << *G << "\n");
1876 return false;
1877 }
1878
1879 if (TargetTriple.isOSBinFormatMachO()) {
1880 StringRef ParsedSegment, ParsedSection;
1881 unsigned TAA = 0, StubSize = 0;
1882 bool TAAParsed;
1883 std::string ErrorCode = MCSectionMachO::ParseSectionSpecifier(
1884 Section, ParsedSegment, ParsedSection, TAA, TAAParsed, StubSize);
1885 assert(ErrorCode.empty() && "Invalid section specifier.");
1886
1887 // Ignore the globals from the __OBJC section. The ObjC runtime assumes
1888 // those conform to /usr/lib/objc/runtime.h, so we can't add redzones to
1889 // them.
1890 if (ParsedSegment == "__OBJC" ||
1891 (ParsedSegment == "__DATA" && ParsedSection.startswith("__objc_"))) {
1892 LLVM_DEBUG(dbgs() << "Ignoring ObjC runtime global: " << *G << "\n");
1893 return false;
1894 }
1895 // See https://github.com/google/sanitizers/issues/32
1896 // Constant CFString instances are compiled in the following way:
1897 // -- the string buffer is emitted into
1898 // __TEXT,__cstring,cstring_literals
1899 // -- the constant NSConstantString structure referencing that buffer
1900 // is placed into __DATA,__cfstring
1901 // Therefore there's no point in placing redzones into __DATA,__cfstring.
1902 // Moreover, it causes the linker to crash on OS X 10.7
1903 if (ParsedSegment == "__DATA" && ParsedSection == "__cfstring") {
1904 LLVM_DEBUG(dbgs() << "Ignoring CFString: " << *G << "\n");
1905 return false;
1906 }
1907 // The linker merges the contents of cstring_literals and removes the
1908 // trailing zeroes.
1909 if (ParsedSegment == "__TEXT" && (TAA & MachO::S_CSTRING_LITERALS)) {
1910 LLVM_DEBUG(dbgs() << "Ignoring a cstring literal: " << *G << "\n");
1911 return false;
1912 }
1913 }
1914 }
1915
1916 return true;
1917 }
1918
1919 // On Mach-O platforms, we emit global metadata in a separate section of the
1920 // binary in order to allow the linker to properly dead strip. This is only
1921 // supported on recent versions of ld64.
ShouldUseMachOGlobalsSection() const1922 bool ModuleAddressSanitizer::ShouldUseMachOGlobalsSection() const {
1923 if (!TargetTriple.isOSBinFormatMachO())
1924 return false;
1925
1926 if (TargetTriple.isMacOSX() && !TargetTriple.isMacOSXVersionLT(10, 11))
1927 return true;
1928 if (TargetTriple.isiOS() /* or tvOS */ && !TargetTriple.isOSVersionLT(9))
1929 return true;
1930 if (TargetTriple.isWatchOS() && !TargetTriple.isOSVersionLT(2))
1931 return true;
1932
1933 return false;
1934 }
1935
getGlobalMetadataSection() const1936 StringRef ModuleAddressSanitizer::getGlobalMetadataSection() const {
1937 switch (TargetTriple.getObjectFormat()) {
1938 case Triple::COFF: return ".ASAN$GL";
1939 case Triple::ELF: return "asan_globals";
1940 case Triple::MachO: return "__DATA,__asan_globals,regular";
1941 case Triple::Wasm:
1942 case Triple::XCOFF:
1943 report_fatal_error(
1944 "ModuleAddressSanitizer not implemented for object file format.");
1945 case Triple::UnknownObjectFormat:
1946 break;
1947 }
1948 llvm_unreachable("unsupported object format");
1949 }
1950
initializeCallbacks(Module & M)1951 void ModuleAddressSanitizer::initializeCallbacks(Module &M) {
1952 IRBuilder<> IRB(*C);
1953
1954 // Declare our poisoning and unpoisoning functions.
1955 AsanPoisonGlobals =
1956 M.getOrInsertFunction(kAsanPoisonGlobalsName, IRB.getVoidTy(), IntptrTy);
1957 AsanUnpoisonGlobals =
1958 M.getOrInsertFunction(kAsanUnpoisonGlobalsName, IRB.getVoidTy());
1959
1960 // Declare functions that register/unregister globals.
1961 AsanRegisterGlobals = M.getOrInsertFunction(
1962 kAsanRegisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy);
1963 AsanUnregisterGlobals = M.getOrInsertFunction(
1964 kAsanUnregisterGlobalsName, IRB.getVoidTy(), IntptrTy, IntptrTy);
1965
1966 // Declare the functions that find globals in a shared object and then invoke
1967 // the (un)register function on them.
1968 AsanRegisterImageGlobals = M.getOrInsertFunction(
1969 kAsanRegisterImageGlobalsName, IRB.getVoidTy(), IntptrTy);
1970 AsanUnregisterImageGlobals = M.getOrInsertFunction(
1971 kAsanUnregisterImageGlobalsName, IRB.getVoidTy(), IntptrTy);
1972
1973 AsanRegisterElfGlobals =
1974 M.getOrInsertFunction(kAsanRegisterElfGlobalsName, IRB.getVoidTy(),
1975 IntptrTy, IntptrTy, IntptrTy);
1976 AsanUnregisterElfGlobals =
1977 M.getOrInsertFunction(kAsanUnregisterElfGlobalsName, IRB.getVoidTy(),
1978 IntptrTy, IntptrTy, IntptrTy);
1979 }
1980
1981 // Put the metadata and the instrumented global in the same group. This ensures
1982 // that the metadata is discarded if the instrumented global is discarded.
SetComdatForGlobalMetadata(GlobalVariable * G,GlobalVariable * Metadata,StringRef InternalSuffix)1983 void ModuleAddressSanitizer::SetComdatForGlobalMetadata(
1984 GlobalVariable *G, GlobalVariable *Metadata, StringRef InternalSuffix) {
1985 Module &M = *G->getParent();
1986 Comdat *C = G->getComdat();
1987 if (!C) {
1988 if (!G->hasName()) {
1989 // If G is unnamed, it must be internal. Give it an artificial name
1990 // so we can put it in a comdat.
1991 assert(G->hasLocalLinkage());
1992 G->setName(Twine(kAsanGenPrefix) + "_anon_global");
1993 }
1994
1995 if (!InternalSuffix.empty() && G->hasLocalLinkage()) {
1996 std::string Name = G->getName();
1997 Name += InternalSuffix;
1998 C = M.getOrInsertComdat(Name);
1999 } else {
2000 C = M.getOrInsertComdat(G->getName());
2001 }
2002
2003 // Make this IMAGE_COMDAT_SELECT_NODUPLICATES on COFF. Also upgrade private
2004 // linkage to internal linkage so that a symbol table entry is emitted. This
2005 // is necessary in order to create the comdat group.
2006 if (TargetTriple.isOSBinFormatCOFF()) {
2007 C->setSelectionKind(Comdat::NoDuplicates);
2008 if (G->hasPrivateLinkage())
2009 G->setLinkage(GlobalValue::InternalLinkage);
2010 }
2011 G->setComdat(C);
2012 }
2013
2014 assert(G->hasComdat());
2015 Metadata->setComdat(G->getComdat());
2016 }
2017
2018 // Create a separate metadata global and put it in the appropriate ASan
2019 // global registration section.
2020 GlobalVariable *
CreateMetadataGlobal(Module & M,Constant * Initializer,StringRef OriginalName)2021 ModuleAddressSanitizer::CreateMetadataGlobal(Module &M, Constant *Initializer,
2022 StringRef OriginalName) {
2023 auto Linkage = TargetTriple.isOSBinFormatMachO()
2024 ? GlobalVariable::InternalLinkage
2025 : GlobalVariable::PrivateLinkage;
2026 GlobalVariable *Metadata = new GlobalVariable(
2027 M, Initializer->getType(), false, Linkage, Initializer,
2028 Twine("__asan_global_") + GlobalValue::dropLLVMManglingEscape(OriginalName));
2029 Metadata->setSection(getGlobalMetadataSection());
2030 return Metadata;
2031 }
2032
CreateAsanModuleDtor(Module & M)2033 IRBuilder<> ModuleAddressSanitizer::CreateAsanModuleDtor(Module &M) {
2034 AsanDtorFunction =
2035 Function::Create(FunctionType::get(Type::getVoidTy(*C), false),
2036 GlobalValue::InternalLinkage, kAsanModuleDtorName, &M);
2037 BasicBlock *AsanDtorBB = BasicBlock::Create(*C, "", AsanDtorFunction);
2038
2039 return IRBuilder<>(ReturnInst::Create(*C, AsanDtorBB));
2040 }
2041
InstrumentGlobalsCOFF(IRBuilder<> & IRB,Module & M,ArrayRef<GlobalVariable * > ExtendedGlobals,ArrayRef<Constant * > MetadataInitializers)2042 void ModuleAddressSanitizer::InstrumentGlobalsCOFF(
2043 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
2044 ArrayRef<Constant *> MetadataInitializers) {
2045 assert(ExtendedGlobals.size() == MetadataInitializers.size());
2046 auto &DL = M.getDataLayout();
2047
2048 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
2049 Constant *Initializer = MetadataInitializers[i];
2050 GlobalVariable *G = ExtendedGlobals[i];
2051 GlobalVariable *Metadata =
2052 CreateMetadataGlobal(M, Initializer, G->getName());
2053
2054 // The MSVC linker always inserts padding when linking incrementally. We
2055 // cope with that by aligning each struct to its size, which must be a power
2056 // of two.
2057 unsigned SizeOfGlobalStruct = DL.getTypeAllocSize(Initializer->getType());
2058 assert(isPowerOf2_32(SizeOfGlobalStruct) &&
2059 "global metadata will not be padded appropriately");
2060 Metadata->setAlignment(assumeAligned(SizeOfGlobalStruct));
2061
2062 SetComdatForGlobalMetadata(G, Metadata, "");
2063 }
2064 }
2065
InstrumentGlobalsELF(IRBuilder<> & IRB,Module & M,ArrayRef<GlobalVariable * > ExtendedGlobals,ArrayRef<Constant * > MetadataInitializers,const std::string & UniqueModuleId)2066 void ModuleAddressSanitizer::InstrumentGlobalsELF(
2067 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
2068 ArrayRef<Constant *> MetadataInitializers,
2069 const std::string &UniqueModuleId) {
2070 assert(ExtendedGlobals.size() == MetadataInitializers.size());
2071
2072 SmallVector<GlobalValue *, 16> MetadataGlobals(ExtendedGlobals.size());
2073 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
2074 GlobalVariable *G = ExtendedGlobals[i];
2075 GlobalVariable *Metadata =
2076 CreateMetadataGlobal(M, MetadataInitializers[i], G->getName());
2077 MDNode *MD = MDNode::get(M.getContext(), ValueAsMetadata::get(G));
2078 Metadata->setMetadata(LLVMContext::MD_associated, MD);
2079 MetadataGlobals[i] = Metadata;
2080
2081 SetComdatForGlobalMetadata(G, Metadata, UniqueModuleId);
2082 }
2083
2084 // Update llvm.compiler.used, adding the new metadata globals. This is
2085 // needed so that during LTO these variables stay alive.
2086 if (!MetadataGlobals.empty())
2087 appendToCompilerUsed(M, MetadataGlobals);
2088
2089 // RegisteredFlag serves two purposes. First, we can pass it to dladdr()
2090 // to look up the loaded image that contains it. Second, we can store in it
2091 // whether registration has already occurred, to prevent duplicate
2092 // registration.
2093 //
2094 // Common linkage ensures that there is only one global per shared library.
2095 GlobalVariable *RegisteredFlag = new GlobalVariable(
2096 M, IntptrTy, false, GlobalVariable::CommonLinkage,
2097 ConstantInt::get(IntptrTy, 0), kAsanGlobalsRegisteredFlagName);
2098 RegisteredFlag->setVisibility(GlobalVariable::HiddenVisibility);
2099
2100 // Create start and stop symbols.
2101 GlobalVariable *StartELFMetadata = new GlobalVariable(
2102 M, IntptrTy, false, GlobalVariable::ExternalWeakLinkage, nullptr,
2103 "__start_" + getGlobalMetadataSection());
2104 StartELFMetadata->setVisibility(GlobalVariable::HiddenVisibility);
2105 GlobalVariable *StopELFMetadata = new GlobalVariable(
2106 M, IntptrTy, false, GlobalVariable::ExternalWeakLinkage, nullptr,
2107 "__stop_" + getGlobalMetadataSection());
2108 StopELFMetadata->setVisibility(GlobalVariable::HiddenVisibility);
2109
2110 // Create a call to register the globals with the runtime.
2111 IRB.CreateCall(AsanRegisterElfGlobals,
2112 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy),
2113 IRB.CreatePointerCast(StartELFMetadata, IntptrTy),
2114 IRB.CreatePointerCast(StopELFMetadata, IntptrTy)});
2115
2116 // We also need to unregister globals at the end, e.g., when a shared library
2117 // gets closed.
2118 IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
2119 IRB_Dtor.CreateCall(AsanUnregisterElfGlobals,
2120 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy),
2121 IRB.CreatePointerCast(StartELFMetadata, IntptrTy),
2122 IRB.CreatePointerCast(StopELFMetadata, IntptrTy)});
2123 }
2124
InstrumentGlobalsMachO(IRBuilder<> & IRB,Module & M,ArrayRef<GlobalVariable * > ExtendedGlobals,ArrayRef<Constant * > MetadataInitializers)2125 void ModuleAddressSanitizer::InstrumentGlobalsMachO(
2126 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
2127 ArrayRef<Constant *> MetadataInitializers) {
2128 assert(ExtendedGlobals.size() == MetadataInitializers.size());
2129
2130 // On recent Mach-O platforms, use a structure which binds the liveness of
2131 // the global variable to the metadata struct. Keep the list of "Liveness" GV
2132 // created to be added to llvm.compiler.used
2133 StructType *LivenessTy = StructType::get(IntptrTy, IntptrTy);
2134 SmallVector<GlobalValue *, 16> LivenessGlobals(ExtendedGlobals.size());
2135
2136 for (size_t i = 0; i < ExtendedGlobals.size(); i++) {
2137 Constant *Initializer = MetadataInitializers[i];
2138 GlobalVariable *G = ExtendedGlobals[i];
2139 GlobalVariable *Metadata =
2140 CreateMetadataGlobal(M, Initializer, G->getName());
2141
2142 // On recent Mach-O platforms, we emit the global metadata in a way that
2143 // allows the linker to properly strip dead globals.
2144 auto LivenessBinder =
2145 ConstantStruct::get(LivenessTy, Initializer->getAggregateElement(0u),
2146 ConstantExpr::getPointerCast(Metadata, IntptrTy));
2147 GlobalVariable *Liveness = new GlobalVariable(
2148 M, LivenessTy, false, GlobalVariable::InternalLinkage, LivenessBinder,
2149 Twine("__asan_binder_") + G->getName());
2150 Liveness->setSection("__DATA,__asan_liveness,regular,live_support");
2151 LivenessGlobals[i] = Liveness;
2152 }
2153
2154 // Update llvm.compiler.used, adding the new liveness globals. This is
2155 // needed so that during LTO these variables stay alive. The alternative
2156 // would be to have the linker handling the LTO symbols, but libLTO
2157 // current API does not expose access to the section for each symbol.
2158 if (!LivenessGlobals.empty())
2159 appendToCompilerUsed(M, LivenessGlobals);
2160
2161 // RegisteredFlag serves two purposes. First, we can pass it to dladdr()
2162 // to look up the loaded image that contains it. Second, we can store in it
2163 // whether registration has already occurred, to prevent duplicate
2164 // registration.
2165 //
2166 // common linkage ensures that there is only one global per shared library.
2167 GlobalVariable *RegisteredFlag = new GlobalVariable(
2168 M, IntptrTy, false, GlobalVariable::CommonLinkage,
2169 ConstantInt::get(IntptrTy, 0), kAsanGlobalsRegisteredFlagName);
2170 RegisteredFlag->setVisibility(GlobalVariable::HiddenVisibility);
2171
2172 IRB.CreateCall(AsanRegisterImageGlobals,
2173 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
2174
2175 // We also need to unregister globals at the end, e.g., when a shared library
2176 // gets closed.
2177 IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
2178 IRB_Dtor.CreateCall(AsanUnregisterImageGlobals,
2179 {IRB.CreatePointerCast(RegisteredFlag, IntptrTy)});
2180 }
2181
InstrumentGlobalsWithMetadataArray(IRBuilder<> & IRB,Module & M,ArrayRef<GlobalVariable * > ExtendedGlobals,ArrayRef<Constant * > MetadataInitializers)2182 void ModuleAddressSanitizer::InstrumentGlobalsWithMetadataArray(
2183 IRBuilder<> &IRB, Module &M, ArrayRef<GlobalVariable *> ExtendedGlobals,
2184 ArrayRef<Constant *> MetadataInitializers) {
2185 assert(ExtendedGlobals.size() == MetadataInitializers.size());
2186 unsigned N = ExtendedGlobals.size();
2187 assert(N > 0);
2188
2189 // On platforms that don't have a custom metadata section, we emit an array
2190 // of global metadata structures.
2191 ArrayType *ArrayOfGlobalStructTy =
2192 ArrayType::get(MetadataInitializers[0]->getType(), N);
2193 auto AllGlobals = new GlobalVariable(
2194 M, ArrayOfGlobalStructTy, false, GlobalVariable::InternalLinkage,
2195 ConstantArray::get(ArrayOfGlobalStructTy, MetadataInitializers), "");
2196 if (Mapping.Scale > 3)
2197 AllGlobals->setAlignment(Align(1ULL << Mapping.Scale));
2198
2199 IRB.CreateCall(AsanRegisterGlobals,
2200 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
2201 ConstantInt::get(IntptrTy, N)});
2202
2203 // We also need to unregister globals at the end, e.g., when a shared library
2204 // gets closed.
2205 IRBuilder<> IRB_Dtor = CreateAsanModuleDtor(M);
2206 IRB_Dtor.CreateCall(AsanUnregisterGlobals,
2207 {IRB.CreatePointerCast(AllGlobals, IntptrTy),
2208 ConstantInt::get(IntptrTy, N)});
2209 }
2210
2211 // This function replaces all global variables with new variables that have
2212 // trailing redzones. It also creates a function that poisons
2213 // redzones and inserts this function into llvm.global_ctors.
2214 // Sets *CtorComdat to true if the global registration code emitted into the
2215 // asan constructor is comdat-compatible.
InstrumentGlobals(IRBuilder<> & IRB,Module & M,bool * CtorComdat)2216 bool ModuleAddressSanitizer::InstrumentGlobals(IRBuilder<> &IRB, Module &M,
2217 bool *CtorComdat) {
2218 *CtorComdat = false;
2219
2220 SmallVector<GlobalVariable *, 16> GlobalsToChange;
2221
2222 for (auto &G : M.globals()) {
2223 if (ShouldInstrumentGlobal(&G)) GlobalsToChange.push_back(&G);
2224 }
2225
2226 size_t n = GlobalsToChange.size();
2227 if (n == 0) {
2228 *CtorComdat = true;
2229 return false;
2230 }
2231
2232 auto &DL = M.getDataLayout();
2233
2234 // A global is described by a structure
2235 // size_t beg;
2236 // size_t size;
2237 // size_t size_with_redzone;
2238 // const char *name;
2239 // const char *module_name;
2240 // size_t has_dynamic_init;
2241 // void *source_location;
2242 // size_t odr_indicator;
2243 // We initialize an array of such structures and pass it to a run-time call.
2244 StructType *GlobalStructTy =
2245 StructType::get(IntptrTy, IntptrTy, IntptrTy, IntptrTy, IntptrTy,
2246 IntptrTy, IntptrTy, IntptrTy);
2247 SmallVector<GlobalVariable *, 16> NewGlobals(n);
2248 SmallVector<Constant *, 16> Initializers(n);
2249
2250 bool HasDynamicallyInitializedGlobals = false;
2251
2252 // We shouldn't merge same module names, as this string serves as unique
2253 // module ID in runtime.
2254 GlobalVariable *ModuleName = createPrivateGlobalForString(
2255 M, M.getModuleIdentifier(), /*AllowMerging*/ false, kAsanGenPrefix);
2256
2257 for (size_t i = 0; i < n; i++) {
2258 static const uint64_t kMaxGlobalRedzone = 1 << 18;
2259 GlobalVariable *G = GlobalsToChange[i];
2260
2261 // FIXME: Metadata should be attched directly to the global directly instead
2262 // of being added to llvm.asan.globals.
2263 auto MD = GlobalsMD.get(G);
2264 StringRef NameForGlobal = G->getName();
2265 // Create string holding the global name (use global name from metadata
2266 // if it's available, otherwise just write the name of global variable).
2267 GlobalVariable *Name = createPrivateGlobalForString(
2268 M, MD.Name.empty() ? NameForGlobal : MD.Name,
2269 /*AllowMerging*/ true, kAsanGenPrefix);
2270
2271 Type *Ty = G->getValueType();
2272 uint64_t SizeInBytes = DL.getTypeAllocSize(Ty);
2273 uint64_t MinRZ = MinRedzoneSizeForGlobal();
2274 // MinRZ <= RZ <= kMaxGlobalRedzone
2275 // and trying to make RZ to be ~ 1/4 of SizeInBytes.
2276 uint64_t RZ = std::max(
2277 MinRZ, std::min(kMaxGlobalRedzone, (SizeInBytes / MinRZ / 4) * MinRZ));
2278 uint64_t RightRedzoneSize = RZ;
2279 // Round up to MinRZ
2280 if (SizeInBytes % MinRZ) RightRedzoneSize += MinRZ - (SizeInBytes % MinRZ);
2281 assert(((RightRedzoneSize + SizeInBytes) % MinRZ) == 0);
2282 Type *RightRedZoneTy = ArrayType::get(IRB.getInt8Ty(), RightRedzoneSize);
2283
2284 StructType *NewTy = StructType::get(Ty, RightRedZoneTy);
2285 Constant *NewInitializer = ConstantStruct::get(
2286 NewTy, G->getInitializer(), Constant::getNullValue(RightRedZoneTy));
2287
2288 // Create a new global variable with enough space for a redzone.
2289 GlobalValue::LinkageTypes Linkage = G->getLinkage();
2290 if (G->isConstant() && Linkage == GlobalValue::PrivateLinkage)
2291 Linkage = GlobalValue::InternalLinkage;
2292 GlobalVariable *NewGlobal =
2293 new GlobalVariable(M, NewTy, G->isConstant(), Linkage, NewInitializer,
2294 "", G, G->getThreadLocalMode());
2295 NewGlobal->copyAttributesFrom(G);
2296 NewGlobal->setComdat(G->getComdat());
2297 NewGlobal->setAlignment(MaybeAlign(MinRZ));
2298 // Don't fold globals with redzones. ODR violation detector and redzone
2299 // poisoning implicitly creates a dependence on the global's address, so it
2300 // is no longer valid for it to be marked unnamed_addr.
2301 NewGlobal->setUnnamedAddr(GlobalValue::UnnamedAddr::None);
2302
2303 // Move null-terminated C strings to "__asan_cstring" section on Darwin.
2304 if (TargetTriple.isOSBinFormatMachO() && !G->hasSection() &&
2305 G->isConstant()) {
2306 auto Seq = dyn_cast<ConstantDataSequential>(G->getInitializer());
2307 if (Seq && Seq->isCString())
2308 NewGlobal->setSection("__TEXT,__asan_cstring,regular");
2309 }
2310
2311 // Transfer the debug info. The payload starts at offset zero so we can
2312 // copy the debug info over as is.
2313 SmallVector<DIGlobalVariableExpression *, 1> GVs;
2314 G->getDebugInfo(GVs);
2315 for (auto *GV : GVs)
2316 NewGlobal->addDebugInfo(GV);
2317
2318 Value *Indices2[2];
2319 Indices2[0] = IRB.getInt32(0);
2320 Indices2[1] = IRB.getInt32(0);
2321
2322 G->replaceAllUsesWith(
2323 ConstantExpr::getGetElementPtr(NewTy, NewGlobal, Indices2, true));
2324 NewGlobal->takeName(G);
2325 G->eraseFromParent();
2326 NewGlobals[i] = NewGlobal;
2327
2328 Constant *SourceLoc;
2329 if (!MD.SourceLoc.empty()) {
2330 auto SourceLocGlobal = createPrivateGlobalForSourceLoc(M, MD.SourceLoc);
2331 SourceLoc = ConstantExpr::getPointerCast(SourceLocGlobal, IntptrTy);
2332 } else {
2333 SourceLoc = ConstantInt::get(IntptrTy, 0);
2334 }
2335
2336 Constant *ODRIndicator = ConstantExpr::getNullValue(IRB.getInt8PtrTy());
2337 GlobalValue *InstrumentedGlobal = NewGlobal;
2338
2339 bool CanUsePrivateAliases =
2340 TargetTriple.isOSBinFormatELF() || TargetTriple.isOSBinFormatMachO() ||
2341 TargetTriple.isOSBinFormatWasm();
2342 if (CanUsePrivateAliases && UsePrivateAlias) {
2343 // Create local alias for NewGlobal to avoid crash on ODR between
2344 // instrumented and non-instrumented libraries.
2345 InstrumentedGlobal =
2346 GlobalAlias::create(GlobalValue::PrivateLinkage, "", NewGlobal);
2347 }
2348
2349 // ODR should not happen for local linkage.
2350 if (NewGlobal->hasLocalLinkage()) {
2351 ODRIndicator = ConstantExpr::getIntToPtr(ConstantInt::get(IntptrTy, -1),
2352 IRB.getInt8PtrTy());
2353 } else if (UseOdrIndicator) {
2354 // With local aliases, we need to provide another externally visible
2355 // symbol __odr_asan_XXX to detect ODR violation.
2356 auto *ODRIndicatorSym =
2357 new GlobalVariable(M, IRB.getInt8Ty(), false, Linkage,
2358 Constant::getNullValue(IRB.getInt8Ty()),
2359 kODRGenPrefix + NameForGlobal, nullptr,
2360 NewGlobal->getThreadLocalMode());
2361
2362 // Set meaningful attributes for indicator symbol.
2363 ODRIndicatorSym->setVisibility(NewGlobal->getVisibility());
2364 ODRIndicatorSym->setDLLStorageClass(NewGlobal->getDLLStorageClass());
2365 ODRIndicatorSym->setAlignment(Align::None());
2366 ODRIndicator = ODRIndicatorSym;
2367 }
2368
2369 Constant *Initializer = ConstantStruct::get(
2370 GlobalStructTy,
2371 ConstantExpr::getPointerCast(InstrumentedGlobal, IntptrTy),
2372 ConstantInt::get(IntptrTy, SizeInBytes),
2373 ConstantInt::get(IntptrTy, SizeInBytes + RightRedzoneSize),
2374 ConstantExpr::getPointerCast(Name, IntptrTy),
2375 ConstantExpr::getPointerCast(ModuleName, IntptrTy),
2376 ConstantInt::get(IntptrTy, MD.IsDynInit), SourceLoc,
2377 ConstantExpr::getPointerCast(ODRIndicator, IntptrTy));
2378
2379 if (ClInitializers && MD.IsDynInit) HasDynamicallyInitializedGlobals = true;
2380
2381 LLVM_DEBUG(dbgs() << "NEW GLOBAL: " << *NewGlobal << "\n");
2382
2383 Initializers[i] = Initializer;
2384 }
2385
2386 // Add instrumented globals to llvm.compiler.used list to avoid LTO from
2387 // ConstantMerge'ing them.
2388 SmallVector<GlobalValue *, 16> GlobalsToAddToUsedList;
2389 for (size_t i = 0; i < n; i++) {
2390 GlobalVariable *G = NewGlobals[i];
2391 if (G->getName().empty()) continue;
2392 GlobalsToAddToUsedList.push_back(G);
2393 }
2394 appendToCompilerUsed(M, ArrayRef<GlobalValue *>(GlobalsToAddToUsedList));
2395
2396 std::string ELFUniqueModuleId =
2397 (UseGlobalsGC && TargetTriple.isOSBinFormatELF()) ? getUniqueModuleId(&M)
2398 : "";
2399
2400 if (!ELFUniqueModuleId.empty()) {
2401 InstrumentGlobalsELF(IRB, M, NewGlobals, Initializers, ELFUniqueModuleId);
2402 *CtorComdat = true;
2403 } else if (UseGlobalsGC && TargetTriple.isOSBinFormatCOFF()) {
2404 InstrumentGlobalsCOFF(IRB, M, NewGlobals, Initializers);
2405 } else if (UseGlobalsGC && ShouldUseMachOGlobalsSection()) {
2406 InstrumentGlobalsMachO(IRB, M, NewGlobals, Initializers);
2407 } else {
2408 InstrumentGlobalsWithMetadataArray(IRB, M, NewGlobals, Initializers);
2409 }
2410
2411 // Create calls for poisoning before initializers run and unpoisoning after.
2412 if (HasDynamicallyInitializedGlobals)
2413 createInitializerPoisonCalls(M, ModuleName);
2414
2415 LLVM_DEBUG(dbgs() << M);
2416 return true;
2417 }
2418
GetAsanVersion(const Module & M) const2419 int ModuleAddressSanitizer::GetAsanVersion(const Module &M) const {
2420 int LongSize = M.getDataLayout().getPointerSizeInBits();
2421 bool isAndroid = Triple(M.getTargetTriple()).isAndroid();
2422 int Version = 8;
2423 // 32-bit Android is one version ahead because of the switch to dynamic
2424 // shadow.
2425 Version += (LongSize == 32 && isAndroid);
2426 return Version;
2427 }
2428
instrumentModule(Module & M)2429 bool ModuleAddressSanitizer::instrumentModule(Module &M) {
2430 initializeCallbacks(M);
2431
2432 if (CompileKernel)
2433 return false;
2434
2435 // Create a module constructor. A destructor is created lazily because not all
2436 // platforms, and not all modules need it.
2437 std::string AsanVersion = std::to_string(GetAsanVersion(M));
2438 std::string VersionCheckName =
2439 ClInsertVersionCheck ? (kAsanVersionCheckNamePrefix + AsanVersion) : "";
2440 std::tie(AsanCtorFunction, std::ignore) = createSanitizerCtorAndInitFunctions(
2441 M, kAsanModuleCtorName, kAsanInitName, /*InitArgTypes=*/{},
2442 /*InitArgs=*/{}, VersionCheckName);
2443
2444 bool CtorComdat = true;
2445 // TODO(glider): temporarily disabled globals instrumentation for KASan.
2446 if (ClGlobals) {
2447 IRBuilder<> IRB(AsanCtorFunction->getEntryBlock().getTerminator());
2448 InstrumentGlobals(IRB, M, &CtorComdat);
2449 }
2450
2451 const uint64_t Priority = GetCtorAndDtorPriority(TargetTriple);
2452
2453 // Put the constructor and destructor in comdat if both
2454 // (1) global instrumentation is not TU-specific
2455 // (2) target is ELF.
2456 if (UseCtorComdat && TargetTriple.isOSBinFormatELF() && CtorComdat) {
2457 AsanCtorFunction->setComdat(M.getOrInsertComdat(kAsanModuleCtorName));
2458 appendToGlobalCtors(M, AsanCtorFunction, Priority, AsanCtorFunction);
2459 if (AsanDtorFunction) {
2460 AsanDtorFunction->setComdat(M.getOrInsertComdat(kAsanModuleDtorName));
2461 appendToGlobalDtors(M, AsanDtorFunction, Priority, AsanDtorFunction);
2462 }
2463 } else {
2464 appendToGlobalCtors(M, AsanCtorFunction, Priority);
2465 if (AsanDtorFunction)
2466 appendToGlobalDtors(M, AsanDtorFunction, Priority);
2467 }
2468
2469 return true;
2470 }
2471
initializeCallbacks(Module & M)2472 void AddressSanitizer::initializeCallbacks(Module &M) {
2473 IRBuilder<> IRB(*C);
2474 // Create __asan_report* callbacks.
2475 // IsWrite, TypeSize and Exp are encoded in the function name.
2476 for (int Exp = 0; Exp < 2; Exp++) {
2477 for (size_t AccessIsWrite = 0; AccessIsWrite <= 1; AccessIsWrite++) {
2478 const std::string TypeStr = AccessIsWrite ? "store" : "load";
2479 const std::string ExpStr = Exp ? "exp_" : "";
2480 const std::string EndingStr = Recover ? "_noabort" : "";
2481
2482 SmallVector<Type *, 3> Args2 = {IntptrTy, IntptrTy};
2483 SmallVector<Type *, 2> Args1{1, IntptrTy};
2484 if (Exp) {
2485 Type *ExpType = Type::getInt32Ty(*C);
2486 Args2.push_back(ExpType);
2487 Args1.push_back(ExpType);
2488 }
2489 AsanErrorCallbackSized[AccessIsWrite][Exp] = M.getOrInsertFunction(
2490 kAsanReportErrorTemplate + ExpStr + TypeStr + "_n" + EndingStr,
2491 FunctionType::get(IRB.getVoidTy(), Args2, false));
2492
2493 AsanMemoryAccessCallbackSized[AccessIsWrite][Exp] = M.getOrInsertFunction(
2494 ClMemoryAccessCallbackPrefix + ExpStr + TypeStr + "N" + EndingStr,
2495 FunctionType::get(IRB.getVoidTy(), Args2, false));
2496
2497 for (size_t AccessSizeIndex = 0; AccessSizeIndex < kNumberOfAccessSizes;
2498 AccessSizeIndex++) {
2499 const std::string Suffix = TypeStr + itostr(1ULL << AccessSizeIndex);
2500 AsanErrorCallback[AccessIsWrite][Exp][AccessSizeIndex] =
2501 M.getOrInsertFunction(
2502 kAsanReportErrorTemplate + ExpStr + Suffix + EndingStr,
2503 FunctionType::get(IRB.getVoidTy(), Args1, false));
2504
2505 AsanMemoryAccessCallback[AccessIsWrite][Exp][AccessSizeIndex] =
2506 M.getOrInsertFunction(
2507 ClMemoryAccessCallbackPrefix + ExpStr + Suffix + EndingStr,
2508 FunctionType::get(IRB.getVoidTy(), Args1, false));
2509 }
2510 }
2511 }
2512
2513 const std::string MemIntrinCallbackPrefix =
2514 CompileKernel ? std::string("") : ClMemoryAccessCallbackPrefix;
2515 AsanMemmove = M.getOrInsertFunction(MemIntrinCallbackPrefix + "memmove",
2516 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
2517 IRB.getInt8PtrTy(), IntptrTy);
2518 AsanMemcpy = M.getOrInsertFunction(MemIntrinCallbackPrefix + "memcpy",
2519 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
2520 IRB.getInt8PtrTy(), IntptrTy);
2521 AsanMemset = M.getOrInsertFunction(MemIntrinCallbackPrefix + "memset",
2522 IRB.getInt8PtrTy(), IRB.getInt8PtrTy(),
2523 IRB.getInt32Ty(), IntptrTy);
2524
2525 AsanHandleNoReturnFunc =
2526 M.getOrInsertFunction(kAsanHandleNoReturnName, IRB.getVoidTy());
2527
2528 AsanPtrCmpFunction =
2529 M.getOrInsertFunction(kAsanPtrCmp, IRB.getVoidTy(), IntptrTy, IntptrTy);
2530 AsanPtrSubFunction =
2531 M.getOrInsertFunction(kAsanPtrSub, IRB.getVoidTy(), IntptrTy, IntptrTy);
2532 // We insert an empty inline asm after __asan_report* to avoid callback merge.
2533 EmptyAsm = InlineAsm::get(FunctionType::get(IRB.getVoidTy(), false),
2534 StringRef(""), StringRef(""),
2535 /*hasSideEffects=*/true);
2536 if (Mapping.InGlobal)
2537 AsanShadowGlobal = M.getOrInsertGlobal("__asan_shadow",
2538 ArrayType::get(IRB.getInt8Ty(), 0));
2539 }
2540
maybeInsertAsanInitAtFunctionEntry(Function & F)2541 bool AddressSanitizer::maybeInsertAsanInitAtFunctionEntry(Function &F) {
2542 // For each NSObject descendant having a +load method, this method is invoked
2543 // by the ObjC runtime before any of the static constructors is called.
2544 // Therefore we need to instrument such methods with a call to __asan_init
2545 // at the beginning in order to initialize our runtime before any access to
2546 // the shadow memory.
2547 // We cannot just ignore these methods, because they may call other
2548 // instrumented functions.
2549 if (F.getName().find(" load]") != std::string::npos) {
2550 FunctionCallee AsanInitFunction =
2551 declareSanitizerInitFunction(*F.getParent(), kAsanInitName, {});
2552 IRBuilder<> IRB(&F.front(), F.front().begin());
2553 IRB.CreateCall(AsanInitFunction, {});
2554 return true;
2555 }
2556 return false;
2557 }
2558
maybeInsertDynamicShadowAtFunctionEntry(Function & F)2559 void AddressSanitizer::maybeInsertDynamicShadowAtFunctionEntry(Function &F) {
2560 // Generate code only when dynamic addressing is needed.
2561 if (Mapping.Offset != kDynamicShadowSentinel)
2562 return;
2563
2564 IRBuilder<> IRB(&F.front().front());
2565 if (Mapping.InGlobal) {
2566 if (ClWithIfuncSuppressRemat) {
2567 // An empty inline asm with input reg == output reg.
2568 // An opaque pointer-to-int cast, basically.
2569 InlineAsm *Asm = InlineAsm::get(
2570 FunctionType::get(IntptrTy, {AsanShadowGlobal->getType()}, false),
2571 StringRef(""), StringRef("=r,0"),
2572 /*hasSideEffects=*/false);
2573 LocalDynamicShadow =
2574 IRB.CreateCall(Asm, {AsanShadowGlobal}, ".asan.shadow");
2575 } else {
2576 LocalDynamicShadow =
2577 IRB.CreatePointerCast(AsanShadowGlobal, IntptrTy, ".asan.shadow");
2578 }
2579 } else {
2580 Value *GlobalDynamicAddress = F.getParent()->getOrInsertGlobal(
2581 kAsanShadowMemoryDynamicAddress, IntptrTy);
2582 LocalDynamicShadow = IRB.CreateLoad(IntptrTy, GlobalDynamicAddress);
2583 }
2584 }
2585
markEscapedLocalAllocas(Function & F)2586 void AddressSanitizer::markEscapedLocalAllocas(Function &F) {
2587 // Find the one possible call to llvm.localescape and pre-mark allocas passed
2588 // to it as uninteresting. This assumes we haven't started processing allocas
2589 // yet. This check is done up front because iterating the use list in
2590 // isInterestingAlloca would be algorithmically slower.
2591 assert(ProcessedAllocas.empty() && "must process localescape before allocas");
2592
2593 // Try to get the declaration of llvm.localescape. If it's not in the module,
2594 // we can exit early.
2595 if (!F.getParent()->getFunction("llvm.localescape")) return;
2596
2597 // Look for a call to llvm.localescape call in the entry block. It can't be in
2598 // any other block.
2599 for (Instruction &I : F.getEntryBlock()) {
2600 IntrinsicInst *II = dyn_cast<IntrinsicInst>(&I);
2601 if (II && II->getIntrinsicID() == Intrinsic::localescape) {
2602 // We found a call. Mark all the allocas passed in as uninteresting.
2603 for (Value *Arg : II->arg_operands()) {
2604 AllocaInst *AI = dyn_cast<AllocaInst>(Arg->stripPointerCasts());
2605 assert(AI && AI->isStaticAlloca() &&
2606 "non-static alloca arg to localescape");
2607 ProcessedAllocas[AI] = false;
2608 }
2609 break;
2610 }
2611 }
2612 }
2613
instrumentFunction(Function & F,const TargetLibraryInfo * TLI)2614 bool AddressSanitizer::instrumentFunction(Function &F,
2615 const TargetLibraryInfo *TLI) {
2616 if (F.getLinkage() == GlobalValue::AvailableExternallyLinkage) return false;
2617 if (!ClDebugFunc.empty() && ClDebugFunc == F.getName()) return false;
2618 if (F.getName().startswith("__asan_")) return false;
2619
2620 bool FunctionModified = false;
2621
2622 // If needed, insert __asan_init before checking for SanitizeAddress attr.
2623 // This function needs to be called even if the function body is not
2624 // instrumented.
2625 if (maybeInsertAsanInitAtFunctionEntry(F))
2626 FunctionModified = true;
2627
2628 // Leave if the function doesn't need instrumentation.
2629 if (!F.hasFnAttribute(Attribute::SanitizeAddress)) return FunctionModified;
2630
2631 LLVM_DEBUG(dbgs() << "ASAN instrumenting:\n" << F << "\n");
2632
2633 initializeCallbacks(*F.getParent());
2634
2635 FunctionStateRAII CleanupObj(this);
2636
2637 maybeInsertDynamicShadowAtFunctionEntry(F);
2638
2639 // We can't instrument allocas used with llvm.localescape. Only static allocas
2640 // can be passed to that intrinsic.
2641 markEscapedLocalAllocas(F);
2642
2643 // We want to instrument every address only once per basic block (unless there
2644 // are calls between uses).
2645 SmallPtrSet<Value *, 16> TempsToInstrument;
2646 SmallVector<Instruction *, 16> ToInstrument;
2647 SmallVector<Instruction *, 8> NoReturnCalls;
2648 SmallVector<BasicBlock *, 16> AllBlocks;
2649 SmallVector<Instruction *, 16> PointerComparisonsOrSubtracts;
2650 int NumAllocas = 0;
2651 bool IsWrite;
2652 unsigned Alignment;
2653 uint64_t TypeSize;
2654
2655 // Fill the set of memory operations to instrument.
2656 for (auto &BB : F) {
2657 AllBlocks.push_back(&BB);
2658 TempsToInstrument.clear();
2659 int NumInsnsPerBB = 0;
2660 for (auto &Inst : BB) {
2661 if (LooksLikeCodeInBug11395(&Inst)) return false;
2662 Value *MaybeMask = nullptr;
2663 if (Value *Addr = isInterestingMemoryAccess(&Inst, &IsWrite, &TypeSize,
2664 &Alignment, &MaybeMask)) {
2665 if (ClOpt && ClOptSameTemp) {
2666 // If we have a mask, skip instrumentation if we've already
2667 // instrumented the full object. But don't add to TempsToInstrument
2668 // because we might get another load/store with a different mask.
2669 if (MaybeMask) {
2670 if (TempsToInstrument.count(Addr))
2671 continue; // We've seen this (whole) temp in the current BB.
2672 } else {
2673 if (!TempsToInstrument.insert(Addr).second)
2674 continue; // We've seen this temp in the current BB.
2675 }
2676 }
2677 } else if (((ClInvalidPointerPairs || ClInvalidPointerCmp) &&
2678 isInterestingPointerComparison(&Inst)) ||
2679 ((ClInvalidPointerPairs || ClInvalidPointerSub) &&
2680 isInterestingPointerSubtraction(&Inst))) {
2681 PointerComparisonsOrSubtracts.push_back(&Inst);
2682 continue;
2683 } else if (isa<MemIntrinsic>(Inst)) {
2684 // ok, take it.
2685 } else {
2686 if (isa<AllocaInst>(Inst)) NumAllocas++;
2687 CallSite CS(&Inst);
2688 if (CS) {
2689 // A call inside BB.
2690 TempsToInstrument.clear();
2691 if (CS.doesNotReturn() && !CS->hasMetadata("nosanitize"))
2692 NoReturnCalls.push_back(CS.getInstruction());
2693 }
2694 if (CallInst *CI = dyn_cast<CallInst>(&Inst))
2695 maybeMarkSanitizerLibraryCallNoBuiltin(CI, TLI);
2696 continue;
2697 }
2698 ToInstrument.push_back(&Inst);
2699 NumInsnsPerBB++;
2700 if (NumInsnsPerBB >= ClMaxInsnsToInstrumentPerBB) break;
2701 }
2702 }
2703
2704 bool UseCalls =
2705 (ClInstrumentationWithCallsThreshold >= 0 &&
2706 ToInstrument.size() > (unsigned)ClInstrumentationWithCallsThreshold);
2707 const DataLayout &DL = F.getParent()->getDataLayout();
2708 ObjectSizeOpts ObjSizeOpts;
2709 ObjSizeOpts.RoundToAlign = true;
2710 ObjectSizeOffsetVisitor ObjSizeVis(DL, TLI, F.getContext(), ObjSizeOpts);
2711
2712 // Instrument.
2713 int NumInstrumented = 0;
2714 for (auto Inst : ToInstrument) {
2715 if (ClDebugMin < 0 || ClDebugMax < 0 ||
2716 (NumInstrumented >= ClDebugMin && NumInstrumented <= ClDebugMax)) {
2717 if (isInterestingMemoryAccess(Inst, &IsWrite, &TypeSize, &Alignment))
2718 instrumentMop(ObjSizeVis, Inst, UseCalls,
2719 F.getParent()->getDataLayout());
2720 else
2721 instrumentMemIntrinsic(cast<MemIntrinsic>(Inst));
2722 }
2723 NumInstrumented++;
2724 }
2725
2726 FunctionStackPoisoner FSP(F, *this);
2727 bool ChangedStack = FSP.runOnFunction();
2728
2729 // We must unpoison the stack before NoReturn calls (throw, _exit, etc).
2730 // See e.g. https://github.com/google/sanitizers/issues/37
2731 for (auto CI : NoReturnCalls) {
2732 IRBuilder<> IRB(CI);
2733 IRB.CreateCall(AsanHandleNoReturnFunc, {});
2734 }
2735
2736 for (auto Inst : PointerComparisonsOrSubtracts) {
2737 instrumentPointerComparisonOrSubtraction(Inst);
2738 NumInstrumented++;
2739 }
2740
2741 if (NumInstrumented > 0 || ChangedStack || !NoReturnCalls.empty())
2742 FunctionModified = true;
2743
2744 LLVM_DEBUG(dbgs() << "ASAN done instrumenting: " << FunctionModified << " "
2745 << F << "\n");
2746
2747 return FunctionModified;
2748 }
2749
2750 // Workaround for bug 11395: we don't want to instrument stack in functions
2751 // with large assembly blobs (32-bit only), otherwise reg alloc may crash.
2752 // FIXME: remove once the bug 11395 is fixed.
LooksLikeCodeInBug11395(Instruction * I)2753 bool AddressSanitizer::LooksLikeCodeInBug11395(Instruction *I) {
2754 if (LongSize != 32) return false;
2755 CallInst *CI = dyn_cast<CallInst>(I);
2756 if (!CI || !CI->isInlineAsm()) return false;
2757 if (CI->getNumArgOperands() <= 5) return false;
2758 // We have inline assembly with quite a few arguments.
2759 return true;
2760 }
2761
initializeCallbacks(Module & M)2762 void FunctionStackPoisoner::initializeCallbacks(Module &M) {
2763 IRBuilder<> IRB(*C);
2764 for (int i = 0; i <= kMaxAsanStackMallocSizeClass; i++) {
2765 std::string Suffix = itostr(i);
2766 AsanStackMallocFunc[i] = M.getOrInsertFunction(
2767 kAsanStackMallocNameTemplate + Suffix, IntptrTy, IntptrTy);
2768 AsanStackFreeFunc[i] =
2769 M.getOrInsertFunction(kAsanStackFreeNameTemplate + Suffix,
2770 IRB.getVoidTy(), IntptrTy, IntptrTy);
2771 }
2772 if (ASan.UseAfterScope) {
2773 AsanPoisonStackMemoryFunc = M.getOrInsertFunction(
2774 kAsanPoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy);
2775 AsanUnpoisonStackMemoryFunc = M.getOrInsertFunction(
2776 kAsanUnpoisonStackMemoryName, IRB.getVoidTy(), IntptrTy, IntptrTy);
2777 }
2778
2779 for (size_t Val : {0x00, 0xf1, 0xf2, 0xf3, 0xf5, 0xf8}) {
2780 std::ostringstream Name;
2781 Name << kAsanSetShadowPrefix;
2782 Name << std::setw(2) << std::setfill('0') << std::hex << Val;
2783 AsanSetShadowFunc[Val] =
2784 M.getOrInsertFunction(Name.str(), IRB.getVoidTy(), IntptrTy, IntptrTy);
2785 }
2786
2787 AsanAllocaPoisonFunc = M.getOrInsertFunction(
2788 kAsanAllocaPoison, IRB.getVoidTy(), IntptrTy, IntptrTy);
2789 AsanAllocasUnpoisonFunc = M.getOrInsertFunction(
2790 kAsanAllocasUnpoison, IRB.getVoidTy(), IntptrTy, IntptrTy);
2791 }
2792
copyToShadowInline(ArrayRef<uint8_t> ShadowMask,ArrayRef<uint8_t> ShadowBytes,size_t Begin,size_t End,IRBuilder<> & IRB,Value * ShadowBase)2793 void FunctionStackPoisoner::copyToShadowInline(ArrayRef<uint8_t> ShadowMask,
2794 ArrayRef<uint8_t> ShadowBytes,
2795 size_t Begin, size_t End,
2796 IRBuilder<> &IRB,
2797 Value *ShadowBase) {
2798 if (Begin >= End)
2799 return;
2800
2801 const size_t LargestStoreSizeInBytes =
2802 std::min<size_t>(sizeof(uint64_t), ASan.LongSize / 8);
2803
2804 const bool IsLittleEndian = F.getParent()->getDataLayout().isLittleEndian();
2805
2806 // Poison given range in shadow using larges store size with out leading and
2807 // trailing zeros in ShadowMask. Zeros never change, so they need neither
2808 // poisoning nor up-poisoning. Still we don't mind if some of them get into a
2809 // middle of a store.
2810 for (size_t i = Begin; i < End;) {
2811 if (!ShadowMask[i]) {
2812 assert(!ShadowBytes[i]);
2813 ++i;
2814 continue;
2815 }
2816
2817 size_t StoreSizeInBytes = LargestStoreSizeInBytes;
2818 // Fit store size into the range.
2819 while (StoreSizeInBytes > End - i)
2820 StoreSizeInBytes /= 2;
2821
2822 // Minimize store size by trimming trailing zeros.
2823 for (size_t j = StoreSizeInBytes - 1; j && !ShadowMask[i + j]; --j) {
2824 while (j <= StoreSizeInBytes / 2)
2825 StoreSizeInBytes /= 2;
2826 }
2827
2828 uint64_t Val = 0;
2829 for (size_t j = 0; j < StoreSizeInBytes; j++) {
2830 if (IsLittleEndian)
2831 Val |= (uint64_t)ShadowBytes[i + j] << (8 * j);
2832 else
2833 Val = (Val << 8) | ShadowBytes[i + j];
2834 }
2835
2836 Value *Ptr = IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i));
2837 Value *Poison = IRB.getIntN(StoreSizeInBytes * 8, Val);
2838 IRB.CreateAlignedStore(
2839 Poison, IRB.CreateIntToPtr(Ptr, Poison->getType()->getPointerTo()), 1);
2840
2841 i += StoreSizeInBytes;
2842 }
2843 }
2844
copyToShadow(ArrayRef<uint8_t> ShadowMask,ArrayRef<uint8_t> ShadowBytes,IRBuilder<> & IRB,Value * ShadowBase)2845 void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
2846 ArrayRef<uint8_t> ShadowBytes,
2847 IRBuilder<> &IRB, Value *ShadowBase) {
2848 copyToShadow(ShadowMask, ShadowBytes, 0, ShadowMask.size(), IRB, ShadowBase);
2849 }
2850
copyToShadow(ArrayRef<uint8_t> ShadowMask,ArrayRef<uint8_t> ShadowBytes,size_t Begin,size_t End,IRBuilder<> & IRB,Value * ShadowBase)2851 void FunctionStackPoisoner::copyToShadow(ArrayRef<uint8_t> ShadowMask,
2852 ArrayRef<uint8_t> ShadowBytes,
2853 size_t Begin, size_t End,
2854 IRBuilder<> &IRB, Value *ShadowBase) {
2855 assert(ShadowMask.size() == ShadowBytes.size());
2856 size_t Done = Begin;
2857 for (size_t i = Begin, j = Begin + 1; i < End; i = j++) {
2858 if (!ShadowMask[i]) {
2859 assert(!ShadowBytes[i]);
2860 continue;
2861 }
2862 uint8_t Val = ShadowBytes[i];
2863 if (!AsanSetShadowFunc[Val])
2864 continue;
2865
2866 // Skip same values.
2867 for (; j < End && ShadowMask[j] && Val == ShadowBytes[j]; ++j) {
2868 }
2869
2870 if (j - i >= ClMaxInlinePoisoningSize) {
2871 copyToShadowInline(ShadowMask, ShadowBytes, Done, i, IRB, ShadowBase);
2872 IRB.CreateCall(AsanSetShadowFunc[Val],
2873 {IRB.CreateAdd(ShadowBase, ConstantInt::get(IntptrTy, i)),
2874 ConstantInt::get(IntptrTy, j - i)});
2875 Done = j;
2876 }
2877 }
2878
2879 copyToShadowInline(ShadowMask, ShadowBytes, Done, End, IRB, ShadowBase);
2880 }
2881
2882 // Fake stack allocator (asan_fake_stack.h) has 11 size classes
2883 // for every power of 2 from kMinStackMallocSize to kMaxAsanStackMallocSizeClass
StackMallocSizeClass(uint64_t LocalStackSize)2884 static int StackMallocSizeClass(uint64_t LocalStackSize) {
2885 assert(LocalStackSize <= kMaxStackMallocSize);
2886 uint64_t MaxSize = kMinStackMallocSize;
2887 for (int i = 0;; i++, MaxSize *= 2)
2888 if (LocalStackSize <= MaxSize) return i;
2889 llvm_unreachable("impossible LocalStackSize");
2890 }
2891
copyArgsPassedByValToAllocas()2892 void FunctionStackPoisoner::copyArgsPassedByValToAllocas() {
2893 Instruction *CopyInsertPoint = &F.front().front();
2894 if (CopyInsertPoint == ASan.LocalDynamicShadow) {
2895 // Insert after the dynamic shadow location is determined
2896 CopyInsertPoint = CopyInsertPoint->getNextNode();
2897 assert(CopyInsertPoint);
2898 }
2899 IRBuilder<> IRB(CopyInsertPoint);
2900 const DataLayout &DL = F.getParent()->getDataLayout();
2901 for (Argument &Arg : F.args()) {
2902 if (Arg.hasByValAttr()) {
2903 Type *Ty = Arg.getType()->getPointerElementType();
2904 const Align Alignment =
2905 DL.getValueOrABITypeAlignment(Arg.getParamAlign(), Ty);
2906
2907 AllocaInst *AI = IRB.CreateAlloca(
2908 Ty, nullptr,
2909 (Arg.hasName() ? Arg.getName() : "Arg" + Twine(Arg.getArgNo())) +
2910 ".byval");
2911 AI->setAlignment(Alignment);
2912 Arg.replaceAllUsesWith(AI);
2913
2914 uint64_t AllocSize = DL.getTypeAllocSize(Ty);
2915 IRB.CreateMemCpy(AI, Alignment, &Arg, Alignment, AllocSize);
2916 }
2917 }
2918 }
2919
createPHI(IRBuilder<> & IRB,Value * Cond,Value * ValueIfTrue,Instruction * ThenTerm,Value * ValueIfFalse)2920 PHINode *FunctionStackPoisoner::createPHI(IRBuilder<> &IRB, Value *Cond,
2921 Value *ValueIfTrue,
2922 Instruction *ThenTerm,
2923 Value *ValueIfFalse) {
2924 PHINode *PHI = IRB.CreatePHI(IntptrTy, 2);
2925 BasicBlock *CondBlock = cast<Instruction>(Cond)->getParent();
2926 PHI->addIncoming(ValueIfFalse, CondBlock);
2927 BasicBlock *ThenBlock = ThenTerm->getParent();
2928 PHI->addIncoming(ValueIfTrue, ThenBlock);
2929 return PHI;
2930 }
2931
createAllocaForLayout(IRBuilder<> & IRB,const ASanStackFrameLayout & L,bool Dynamic)2932 Value *FunctionStackPoisoner::createAllocaForLayout(
2933 IRBuilder<> &IRB, const ASanStackFrameLayout &L, bool Dynamic) {
2934 AllocaInst *Alloca;
2935 if (Dynamic) {
2936 Alloca = IRB.CreateAlloca(IRB.getInt8Ty(),
2937 ConstantInt::get(IRB.getInt64Ty(), L.FrameSize),
2938 "MyAlloca");
2939 } else {
2940 Alloca = IRB.CreateAlloca(ArrayType::get(IRB.getInt8Ty(), L.FrameSize),
2941 nullptr, "MyAlloca");
2942 assert(Alloca->isStaticAlloca());
2943 }
2944 assert((ClRealignStack & (ClRealignStack - 1)) == 0);
2945 size_t FrameAlignment = std::max(L.FrameAlignment, (size_t)ClRealignStack);
2946 Alloca->setAlignment(MaybeAlign(FrameAlignment));
2947 return IRB.CreatePointerCast(Alloca, IntptrTy);
2948 }
2949
createDynamicAllocasInitStorage()2950 void FunctionStackPoisoner::createDynamicAllocasInitStorage() {
2951 BasicBlock &FirstBB = *F.begin();
2952 IRBuilder<> IRB(dyn_cast<Instruction>(FirstBB.begin()));
2953 DynamicAllocaLayout = IRB.CreateAlloca(IntptrTy, nullptr);
2954 IRB.CreateStore(Constant::getNullValue(IntptrTy), DynamicAllocaLayout);
2955 DynamicAllocaLayout->setAlignment(Align(32));
2956 }
2957
processDynamicAllocas()2958 void FunctionStackPoisoner::processDynamicAllocas() {
2959 if (!ClInstrumentDynamicAllocas || DynamicAllocaVec.empty()) {
2960 assert(DynamicAllocaPoisonCallVec.empty());
2961 return;
2962 }
2963
2964 // Insert poison calls for lifetime intrinsics for dynamic allocas.
2965 for (const auto &APC : DynamicAllocaPoisonCallVec) {
2966 assert(APC.InsBefore);
2967 assert(APC.AI);
2968 assert(ASan.isInterestingAlloca(*APC.AI));
2969 assert(!APC.AI->isStaticAlloca());
2970
2971 IRBuilder<> IRB(APC.InsBefore);
2972 poisonAlloca(APC.AI, APC.Size, IRB, APC.DoPoison);
2973 // Dynamic allocas will be unpoisoned unconditionally below in
2974 // unpoisonDynamicAllocas.
2975 // Flag that we need unpoison static allocas.
2976 }
2977
2978 // Handle dynamic allocas.
2979 createDynamicAllocasInitStorage();
2980 for (auto &AI : DynamicAllocaVec)
2981 handleDynamicAllocaCall(AI);
2982 unpoisonDynamicAllocas();
2983 }
2984
processStaticAllocas()2985 void FunctionStackPoisoner::processStaticAllocas() {
2986 if (AllocaVec.empty()) {
2987 assert(StaticAllocaPoisonCallVec.empty());
2988 return;
2989 }
2990
2991 int StackMallocIdx = -1;
2992 DebugLoc EntryDebugLocation;
2993 if (auto SP = F.getSubprogram())
2994 EntryDebugLocation = DebugLoc::get(SP->getScopeLine(), 0, SP);
2995
2996 Instruction *InsBefore = AllocaVec[0];
2997 IRBuilder<> IRB(InsBefore);
2998
2999 // Make sure non-instrumented allocas stay in the entry block. Otherwise,
3000 // debug info is broken, because only entry-block allocas are treated as
3001 // regular stack slots.
3002 auto InsBeforeB = InsBefore->getParent();
3003 assert(InsBeforeB == &F.getEntryBlock());
3004 for (auto *AI : StaticAllocasToMoveUp)
3005 if (AI->getParent() == InsBeforeB)
3006 AI->moveBefore(InsBefore);
3007
3008 // If we have a call to llvm.localescape, keep it in the entry block.
3009 if (LocalEscapeCall) LocalEscapeCall->moveBefore(InsBefore);
3010
3011 SmallVector<ASanStackVariableDescription, 16> SVD;
3012 SVD.reserve(AllocaVec.size());
3013 for (AllocaInst *AI : AllocaVec) {
3014 ASanStackVariableDescription D = {AI->getName().data(),
3015 ASan.getAllocaSizeInBytes(*AI),
3016 0,
3017 AI->getAlignment(),
3018 AI,
3019 0,
3020 0};
3021 SVD.push_back(D);
3022 }
3023
3024 // Minimal header size (left redzone) is 4 pointers,
3025 // i.e. 32 bytes on 64-bit platforms and 16 bytes in 32-bit platforms.
3026 size_t Granularity = 1ULL << Mapping.Scale;
3027 size_t MinHeaderSize = std::max((size_t)ASan.LongSize / 2, Granularity);
3028 const ASanStackFrameLayout &L =
3029 ComputeASanStackFrameLayout(SVD, Granularity, MinHeaderSize);
3030
3031 // Build AllocaToSVDMap for ASanStackVariableDescription lookup.
3032 DenseMap<const AllocaInst *, ASanStackVariableDescription *> AllocaToSVDMap;
3033 for (auto &Desc : SVD)
3034 AllocaToSVDMap[Desc.AI] = &Desc;
3035
3036 // Update SVD with information from lifetime intrinsics.
3037 for (const auto &APC : StaticAllocaPoisonCallVec) {
3038 assert(APC.InsBefore);
3039 assert(APC.AI);
3040 assert(ASan.isInterestingAlloca(*APC.AI));
3041 assert(APC.AI->isStaticAlloca());
3042
3043 ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
3044 Desc.LifetimeSize = Desc.Size;
3045 if (const DILocation *FnLoc = EntryDebugLocation.get()) {
3046 if (const DILocation *LifetimeLoc = APC.InsBefore->getDebugLoc().get()) {
3047 if (LifetimeLoc->getFile() == FnLoc->getFile())
3048 if (unsigned Line = LifetimeLoc->getLine())
3049 Desc.Line = std::min(Desc.Line ? Desc.Line : Line, Line);
3050 }
3051 }
3052 }
3053
3054 auto DescriptionString = ComputeASanStackFrameDescription(SVD);
3055 LLVM_DEBUG(dbgs() << DescriptionString << " --- " << L.FrameSize << "\n");
3056 uint64_t LocalStackSize = L.FrameSize;
3057 bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
3058 LocalStackSize <= kMaxStackMallocSize;
3059 bool DoDynamicAlloca = ClDynamicAllocaStack;
3060 // Don't do dynamic alloca or stack malloc if:
3061 // 1) There is inline asm: too often it makes assumptions on which registers
3062 // are available.
3063 // 2) There is a returns_twice call (typically setjmp), which is
3064 // optimization-hostile, and doesn't play well with introduced indirect
3065 // register-relative calculation of local variable addresses.
3066 DoDynamicAlloca &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
3067 DoStackMalloc &= !HasNonEmptyInlineAsm && !HasReturnsTwiceCall;
3068
3069 Value *StaticAlloca =
3070 DoDynamicAlloca ? nullptr : createAllocaForLayout(IRB, L, false);
3071
3072 Value *FakeStack;
3073 Value *LocalStackBase;
3074 Value *LocalStackBaseAlloca;
3075 uint8_t DIExprFlags = DIExpression::ApplyOffset;
3076
3077 if (DoStackMalloc) {
3078 LocalStackBaseAlloca =
3079 IRB.CreateAlloca(IntptrTy, nullptr, "asan_local_stack_base");
3080 // void *FakeStack = __asan_option_detect_stack_use_after_return
3081 // ? __asan_stack_malloc_N(LocalStackSize)
3082 // : nullptr;
3083 // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
3084 Constant *OptionDetectUseAfterReturn = F.getParent()->getOrInsertGlobal(
3085 kAsanOptionDetectUseAfterReturn, IRB.getInt32Ty());
3086 Value *UseAfterReturnIsEnabled = IRB.CreateICmpNE(
3087 IRB.CreateLoad(IRB.getInt32Ty(), OptionDetectUseAfterReturn),
3088 Constant::getNullValue(IRB.getInt32Ty()));
3089 Instruction *Term =
3090 SplitBlockAndInsertIfThen(UseAfterReturnIsEnabled, InsBefore, false);
3091 IRBuilder<> IRBIf(Term);
3092 StackMallocIdx = StackMallocSizeClass(LocalStackSize);
3093 assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
3094 Value *FakeStackValue =
3095 IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
3096 ConstantInt::get(IntptrTy, LocalStackSize));
3097 IRB.SetInsertPoint(InsBefore);
3098 FakeStack = createPHI(IRB, UseAfterReturnIsEnabled, FakeStackValue, Term,
3099 ConstantInt::get(IntptrTy, 0));
3100
3101 Value *NoFakeStack =
3102 IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
3103 Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
3104 IRBIf.SetInsertPoint(Term);
3105 Value *AllocaValue =
3106 DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
3107
3108 IRB.SetInsertPoint(InsBefore);
3109 LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
3110 IRB.CreateStore(LocalStackBase, LocalStackBaseAlloca);
3111 DIExprFlags |= DIExpression::DerefBefore;
3112 } else {
3113 // void *FakeStack = nullptr;
3114 // void *LocalStackBase = alloca(LocalStackSize);
3115 FakeStack = ConstantInt::get(IntptrTy, 0);
3116 LocalStackBase =
3117 DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
3118 LocalStackBaseAlloca = LocalStackBase;
3119 }
3120
3121 // Replace Alloca instructions with base+offset.
3122 for (const auto &Desc : SVD) {
3123 AllocaInst *AI = Desc.AI;
3124 replaceDbgDeclareForAlloca(AI, LocalStackBaseAlloca, DIB, DIExprFlags,
3125 Desc.Offset);
3126 Value *NewAllocaPtr = IRB.CreateIntToPtr(
3127 IRB.CreateAdd(LocalStackBase, ConstantInt::get(IntptrTy, Desc.Offset)),
3128 AI->getType());
3129 AI->replaceAllUsesWith(NewAllocaPtr);
3130 }
3131
3132 // The left-most redzone has enough space for at least 4 pointers.
3133 // Write the Magic value to redzone[0].
3134 Value *BasePlus0 = IRB.CreateIntToPtr(LocalStackBase, IntptrPtrTy);
3135 IRB.CreateStore(ConstantInt::get(IntptrTy, kCurrentStackFrameMagic),
3136 BasePlus0);
3137 // Write the frame description constant to redzone[1].
3138 Value *BasePlus1 = IRB.CreateIntToPtr(
3139 IRB.CreateAdd(LocalStackBase,
3140 ConstantInt::get(IntptrTy, ASan.LongSize / 8)),
3141 IntptrPtrTy);
3142 GlobalVariable *StackDescriptionGlobal =
3143 createPrivateGlobalForString(*F.getParent(), DescriptionString,
3144 /*AllowMerging*/ true, kAsanGenPrefix);
3145 Value *Description = IRB.CreatePointerCast(StackDescriptionGlobal, IntptrTy);
3146 IRB.CreateStore(Description, BasePlus1);
3147 // Write the PC to redzone[2].
3148 Value *BasePlus2 = IRB.CreateIntToPtr(
3149 IRB.CreateAdd(LocalStackBase,
3150 ConstantInt::get(IntptrTy, 2 * ASan.LongSize / 8)),
3151 IntptrPtrTy);
3152 IRB.CreateStore(IRB.CreatePointerCast(&F, IntptrTy), BasePlus2);
3153
3154 const auto &ShadowAfterScope = GetShadowBytesAfterScope(SVD, L);
3155
3156 // Poison the stack red zones at the entry.
3157 Value *ShadowBase = ASan.memToShadow(LocalStackBase, IRB);
3158 // As mask we must use most poisoned case: red zones and after scope.
3159 // As bytes we can use either the same or just red zones only.
3160 copyToShadow(ShadowAfterScope, ShadowAfterScope, IRB, ShadowBase);
3161
3162 if (!StaticAllocaPoisonCallVec.empty()) {
3163 const auto &ShadowInScope = GetShadowBytes(SVD, L);
3164
3165 // Poison static allocas near lifetime intrinsics.
3166 for (const auto &APC : StaticAllocaPoisonCallVec) {
3167 const ASanStackVariableDescription &Desc = *AllocaToSVDMap[APC.AI];
3168 assert(Desc.Offset % L.Granularity == 0);
3169 size_t Begin = Desc.Offset / L.Granularity;
3170 size_t End = Begin + (APC.Size + L.Granularity - 1) / L.Granularity;
3171
3172 IRBuilder<> IRB(APC.InsBefore);
3173 copyToShadow(ShadowAfterScope,
3174 APC.DoPoison ? ShadowAfterScope : ShadowInScope, Begin, End,
3175 IRB, ShadowBase);
3176 }
3177 }
3178
3179 SmallVector<uint8_t, 64> ShadowClean(ShadowAfterScope.size(), 0);
3180 SmallVector<uint8_t, 64> ShadowAfterReturn;
3181
3182 // (Un)poison the stack before all ret instructions.
3183 for (auto Ret : RetVec) {
3184 IRBuilder<> IRBRet(Ret);
3185 // Mark the current frame as retired.
3186 IRBRet.CreateStore(ConstantInt::get(IntptrTy, kRetiredStackFrameMagic),
3187 BasePlus0);
3188 if (DoStackMalloc) {
3189 assert(StackMallocIdx >= 0);
3190 // if FakeStack != 0 // LocalStackBase == FakeStack
3191 // // In use-after-return mode, poison the whole stack frame.
3192 // if StackMallocIdx <= 4
3193 // // For small sizes inline the whole thing:
3194 // memset(ShadowBase, kAsanStackAfterReturnMagic, ShadowSize);
3195 // **SavedFlagPtr(FakeStack) = 0
3196 // else
3197 // __asan_stack_free_N(FakeStack, LocalStackSize)
3198 // else
3199 // <This is not a fake stack; unpoison the redzones>
3200 Value *Cmp =
3201 IRBRet.CreateICmpNE(FakeStack, Constant::getNullValue(IntptrTy));
3202 Instruction *ThenTerm, *ElseTerm;
3203 SplitBlockAndInsertIfThenElse(Cmp, Ret, &ThenTerm, &ElseTerm);
3204
3205 IRBuilder<> IRBPoison(ThenTerm);
3206 if (StackMallocIdx <= 4) {
3207 int ClassSize = kMinStackMallocSize << StackMallocIdx;
3208 ShadowAfterReturn.resize(ClassSize / L.Granularity,
3209 kAsanStackUseAfterReturnMagic);
3210 copyToShadow(ShadowAfterReturn, ShadowAfterReturn, IRBPoison,
3211 ShadowBase);
3212 Value *SavedFlagPtrPtr = IRBPoison.CreateAdd(
3213 FakeStack,
3214 ConstantInt::get(IntptrTy, ClassSize - ASan.LongSize / 8));
3215 Value *SavedFlagPtr = IRBPoison.CreateLoad(
3216 IntptrTy, IRBPoison.CreateIntToPtr(SavedFlagPtrPtr, IntptrPtrTy));
3217 IRBPoison.CreateStore(
3218 Constant::getNullValue(IRBPoison.getInt8Ty()),
3219 IRBPoison.CreateIntToPtr(SavedFlagPtr, IRBPoison.getInt8PtrTy()));
3220 } else {
3221 // For larger frames call __asan_stack_free_*.
3222 IRBPoison.CreateCall(
3223 AsanStackFreeFunc[StackMallocIdx],
3224 {FakeStack, ConstantInt::get(IntptrTy, LocalStackSize)});
3225 }
3226
3227 IRBuilder<> IRBElse(ElseTerm);
3228 copyToShadow(ShadowAfterScope, ShadowClean, IRBElse, ShadowBase);
3229 } else {
3230 copyToShadow(ShadowAfterScope, ShadowClean, IRBRet, ShadowBase);
3231 }
3232 }
3233
3234 // We are done. Remove the old unused alloca instructions.
3235 for (auto AI : AllocaVec) AI->eraseFromParent();
3236 }
3237
poisonAlloca(Value * V,uint64_t Size,IRBuilder<> & IRB,bool DoPoison)3238 void FunctionStackPoisoner::poisonAlloca(Value *V, uint64_t Size,
3239 IRBuilder<> &IRB, bool DoPoison) {
3240 // For now just insert the call to ASan runtime.
3241 Value *AddrArg = IRB.CreatePointerCast(V, IntptrTy);
3242 Value *SizeArg = ConstantInt::get(IntptrTy, Size);
3243 IRB.CreateCall(
3244 DoPoison ? AsanPoisonStackMemoryFunc : AsanUnpoisonStackMemoryFunc,
3245 {AddrArg, SizeArg});
3246 }
3247
3248 // Handling llvm.lifetime intrinsics for a given %alloca:
3249 // (1) collect all llvm.lifetime.xxx(%size, %value) describing the alloca.
3250 // (2) if %size is constant, poison memory for llvm.lifetime.end (to detect
3251 // invalid accesses) and unpoison it for llvm.lifetime.start (the memory
3252 // could be poisoned by previous llvm.lifetime.end instruction, as the
3253 // variable may go in and out of scope several times, e.g. in loops).
3254 // (3) if we poisoned at least one %alloca in a function,
3255 // unpoison the whole stack frame at function exit.
handleDynamicAllocaCall(AllocaInst * AI)3256 void FunctionStackPoisoner::handleDynamicAllocaCall(AllocaInst *AI) {
3257 IRBuilder<> IRB(AI);
3258
3259 const unsigned Align = std::max(kAllocaRzSize, AI->getAlignment());
3260 const uint64_t AllocaRedzoneMask = kAllocaRzSize - 1;
3261
3262 Value *Zero = Constant::getNullValue(IntptrTy);
3263 Value *AllocaRzSize = ConstantInt::get(IntptrTy, kAllocaRzSize);
3264 Value *AllocaRzMask = ConstantInt::get(IntptrTy, AllocaRedzoneMask);
3265
3266 // Since we need to extend alloca with additional memory to locate
3267 // redzones, and OldSize is number of allocated blocks with
3268 // ElementSize size, get allocated memory size in bytes by
3269 // OldSize * ElementSize.
3270 const unsigned ElementSize =
3271 F.getParent()->getDataLayout().getTypeAllocSize(AI->getAllocatedType());
3272 Value *OldSize =
3273 IRB.CreateMul(IRB.CreateIntCast(AI->getArraySize(), IntptrTy, false),
3274 ConstantInt::get(IntptrTy, ElementSize));
3275
3276 // PartialSize = OldSize % 32
3277 Value *PartialSize = IRB.CreateAnd(OldSize, AllocaRzMask);
3278
3279 // Misalign = kAllocaRzSize - PartialSize;
3280 Value *Misalign = IRB.CreateSub(AllocaRzSize, PartialSize);
3281
3282 // PartialPadding = Misalign != kAllocaRzSize ? Misalign : 0;
3283 Value *Cond = IRB.CreateICmpNE(Misalign, AllocaRzSize);
3284 Value *PartialPadding = IRB.CreateSelect(Cond, Misalign, Zero);
3285
3286 // AdditionalChunkSize = Align + PartialPadding + kAllocaRzSize
3287 // Align is added to locate left redzone, PartialPadding for possible
3288 // partial redzone and kAllocaRzSize for right redzone respectively.
3289 Value *AdditionalChunkSize = IRB.CreateAdd(
3290 ConstantInt::get(IntptrTy, Align + kAllocaRzSize), PartialPadding);
3291
3292 Value *NewSize = IRB.CreateAdd(OldSize, AdditionalChunkSize);
3293
3294 // Insert new alloca with new NewSize and Align params.
3295 AllocaInst *NewAlloca = IRB.CreateAlloca(IRB.getInt8Ty(), NewSize);
3296 NewAlloca->setAlignment(MaybeAlign(Align));
3297
3298 // NewAddress = Address + Align
3299 Value *NewAddress = IRB.CreateAdd(IRB.CreatePtrToInt(NewAlloca, IntptrTy),
3300 ConstantInt::get(IntptrTy, Align));
3301
3302 // Insert __asan_alloca_poison call for new created alloca.
3303 IRB.CreateCall(AsanAllocaPoisonFunc, {NewAddress, OldSize});
3304
3305 // Store the last alloca's address to DynamicAllocaLayout. We'll need this
3306 // for unpoisoning stuff.
3307 IRB.CreateStore(IRB.CreatePtrToInt(NewAlloca, IntptrTy), DynamicAllocaLayout);
3308
3309 Value *NewAddressPtr = IRB.CreateIntToPtr(NewAddress, AI->getType());
3310
3311 // Replace all uses of AddessReturnedByAlloca with NewAddressPtr.
3312 AI->replaceAllUsesWith(NewAddressPtr);
3313
3314 // We are done. Erase old alloca from parent.
3315 AI->eraseFromParent();
3316 }
3317
3318 // isSafeAccess returns true if Addr is always inbounds with respect to its
3319 // base object. For example, it is a field access or an array access with
3320 // constant inbounds index.
isSafeAccess(ObjectSizeOffsetVisitor & ObjSizeVis,Value * Addr,uint64_t TypeSize) const3321 bool AddressSanitizer::isSafeAccess(ObjectSizeOffsetVisitor &ObjSizeVis,
3322 Value *Addr, uint64_t TypeSize) const {
3323 SizeOffsetType SizeOffset = ObjSizeVis.compute(Addr);
3324 if (!ObjSizeVis.bothKnown(SizeOffset)) return false;
3325 uint64_t Size = SizeOffset.first.getZExtValue();
3326 int64_t Offset = SizeOffset.second.getSExtValue();
3327 // Three checks are required to ensure safety:
3328 // . Offset >= 0 (since the offset is given from the base ptr)
3329 // . Size >= Offset (unsigned)
3330 // . Size - Offset >= NeededSize (unsigned)
3331 return Offset >= 0 && Size >= uint64_t(Offset) &&
3332 Size - uint64_t(Offset) >= TypeSize / 8;
3333 }
3334