1 //=== MallocChecker.cpp - A malloc/free checker -------------------*- C++ -*--//
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 defines malloc/free checker, which checks for potential memory
10 // leaks, double free, and use-after-free problems.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "clang/StaticAnalyzer/Checkers/BuiltinCheckerRegistration.h"
15 #include "InterCheckerAPI.h"
16 #include "clang/AST/Attr.h"
17 #include "clang/AST/ParentMap.h"
18 #include "clang/Basic/SourceManager.h"
19 #include "clang/Basic/TargetInfo.h"
20 #include "clang/Lex/Lexer.h"
21 #include "clang/StaticAnalyzer/Core/BugReporter/BugType.h"
22 #include "clang/StaticAnalyzer/Core/BugReporter/CommonBugCategories.h"
23 #include "clang/StaticAnalyzer/Core/Checker.h"
24 #include "clang/StaticAnalyzer/Core/CheckerManager.h"
25 #include "clang/StaticAnalyzer/Core/PathSensitive/CallEvent.h"
26 #include "clang/StaticAnalyzer/Core/PathSensitive/CheckerContext.h"
27 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramState.h"
28 #include "clang/StaticAnalyzer/Core/PathSensitive/ProgramStateTrait.h"
29 #include "clang/StaticAnalyzer/Core/PathSensitive/SymbolManager.h"
30 #include "llvm/ADT/STLExtras.h"
31 #include "llvm/ADT/SmallString.h"
32 #include "llvm/ADT/StringExtras.h"
33 #include "AllocationState.h"
34 #include <climits>
35 #include <utility>
36
37 using namespace clang;
38 using namespace ento;
39
40 namespace {
41
42 // Used to check correspondence between allocators and deallocators.
43 enum AllocationFamily {
44 AF_None,
45 AF_Malloc,
46 AF_CXXNew,
47 AF_CXXNewArray,
48 AF_IfNameIndex,
49 AF_Alloca,
50 AF_InnerBuffer
51 };
52
53 class RefState {
54 enum Kind { // Reference to allocated memory.
55 Allocated,
56 // Reference to zero-allocated memory.
57 AllocatedOfSizeZero,
58 // Reference to released/freed memory.
59 Released,
60 // The responsibility for freeing resources has transferred from
61 // this reference. A relinquished symbol should not be freed.
62 Relinquished,
63 // We are no longer guaranteed to have observed all manipulations
64 // of this pointer/memory. For example, it could have been
65 // passed as a parameter to an opaque function.
66 Escaped
67 };
68
69 const Stmt *S;
70 unsigned K : 3; // Kind enum, but stored as a bitfield.
71 unsigned Family : 29; // Rest of 32-bit word, currently just an allocation
72 // family.
73
RefState(Kind k,const Stmt * s,unsigned family)74 RefState(Kind k, const Stmt *s, unsigned family)
75 : S(s), K(k), Family(family) {
76 assert(family != AF_None);
77 }
78 public:
isAllocated() const79 bool isAllocated() const { return K == Allocated; }
isAllocatedOfSizeZero() const80 bool isAllocatedOfSizeZero() const { return K == AllocatedOfSizeZero; }
isReleased() const81 bool isReleased() const { return K == Released; }
isRelinquished() const82 bool isRelinquished() const { return K == Relinquished; }
isEscaped() const83 bool isEscaped() const { return K == Escaped; }
getAllocationFamily() const84 AllocationFamily getAllocationFamily() const {
85 return (AllocationFamily)Family;
86 }
getStmt() const87 const Stmt *getStmt() const { return S; }
88
operator ==(const RefState & X) const89 bool operator==(const RefState &X) const {
90 return K == X.K && S == X.S && Family == X.Family;
91 }
92
getAllocated(unsigned family,const Stmt * s)93 static RefState getAllocated(unsigned family, const Stmt *s) {
94 return RefState(Allocated, s, family);
95 }
getAllocatedOfSizeZero(const RefState * RS)96 static RefState getAllocatedOfSizeZero(const RefState *RS) {
97 return RefState(AllocatedOfSizeZero, RS->getStmt(),
98 RS->getAllocationFamily());
99 }
getReleased(unsigned family,const Stmt * s)100 static RefState getReleased(unsigned family, const Stmt *s) {
101 return RefState(Released, s, family);
102 }
getRelinquished(unsigned family,const Stmt * s)103 static RefState getRelinquished(unsigned family, const Stmt *s) {
104 return RefState(Relinquished, s, family);
105 }
getEscaped(const RefState * RS)106 static RefState getEscaped(const RefState *RS) {
107 return RefState(Escaped, RS->getStmt(), RS->getAllocationFamily());
108 }
109
Profile(llvm::FoldingSetNodeID & ID) const110 void Profile(llvm::FoldingSetNodeID &ID) const {
111 ID.AddInteger(K);
112 ID.AddPointer(S);
113 ID.AddInteger(Family);
114 }
115
dump(raw_ostream & OS) const116 void dump(raw_ostream &OS) const {
117 switch (static_cast<Kind>(K)) {
118 #define CASE(ID) case ID: OS << #ID; break;
119 CASE(Allocated)
120 CASE(AllocatedOfSizeZero)
121 CASE(Released)
122 CASE(Relinquished)
123 CASE(Escaped)
124 }
125 }
126
dump() const127 LLVM_DUMP_METHOD void dump() const { dump(llvm::errs()); }
128 };
129
130 enum ReallocPairKind {
131 RPToBeFreedAfterFailure,
132 // The symbol has been freed when reallocation failed.
133 RPIsFreeOnFailure,
134 // The symbol does not need to be freed after reallocation fails.
135 RPDoNotTrackAfterFailure
136 };
137
138 /// \class ReallocPair
139 /// Stores information about the symbol being reallocated by a call to
140 /// 'realloc' to allow modeling failed reallocation later in the path.
141 struct ReallocPair {
142 // The symbol which realloc reallocated.
143 SymbolRef ReallocatedSym;
144 ReallocPairKind Kind;
145
ReallocPair__anon29920e0b0111::ReallocPair146 ReallocPair(SymbolRef S, ReallocPairKind K) :
147 ReallocatedSym(S), Kind(K) {}
Profile__anon29920e0b0111::ReallocPair148 void Profile(llvm::FoldingSetNodeID &ID) const {
149 ID.AddInteger(Kind);
150 ID.AddPointer(ReallocatedSym);
151 }
operator ==__anon29920e0b0111::ReallocPair152 bool operator==(const ReallocPair &X) const {
153 return ReallocatedSym == X.ReallocatedSym &&
154 Kind == X.Kind;
155 }
156 };
157
158 typedef std::pair<const ExplodedNode*, const MemRegion*> LeakInfo;
159
160 class MallocChecker : public Checker<check::DeadSymbols,
161 check::PointerEscape,
162 check::ConstPointerEscape,
163 check::PreStmt<ReturnStmt>,
164 check::EndFunction,
165 check::PreCall,
166 check::PostStmt<CallExpr>,
167 check::PostStmt<CXXNewExpr>,
168 check::NewAllocator,
169 check::PreStmt<CXXDeleteExpr>,
170 check::PostStmt<BlockExpr>,
171 check::PostObjCMessage,
172 check::Location,
173 eval::Assume>
174 {
175 public:
MallocChecker()176 MallocChecker()
177 : II_alloca(nullptr), II_win_alloca(nullptr), II_malloc(nullptr),
178 II_free(nullptr), II_realloc(nullptr), II_calloc(nullptr),
179 II_valloc(nullptr), II_reallocf(nullptr), II_strndup(nullptr),
180 II_strdup(nullptr), II_win_strdup(nullptr), II_kmalloc(nullptr),
181 II_kfree(nullptr), II_if_nameindex(nullptr),
182 II_if_freenameindex(nullptr), II_wcsdup(nullptr),
183 II_win_wcsdup(nullptr), II_g_malloc(nullptr), II_g_malloc0(nullptr),
184 II_g_realloc(nullptr), II_g_try_malloc(nullptr),
185 II_g_try_malloc0(nullptr), II_g_try_realloc(nullptr),
186 II_g_free(nullptr), II_g_memdup(nullptr), II_g_malloc_n(nullptr),
187 II_g_malloc0_n(nullptr), II_g_realloc_n(nullptr),
188 II_g_try_malloc_n(nullptr), II_g_try_malloc0_n(nullptr),
189 II_g_try_realloc_n(nullptr) {}
190
191 /// In pessimistic mode, the checker assumes that it does not know which
192 /// functions might free the memory.
193 enum CheckKind {
194 CK_MallocChecker,
195 CK_NewDeleteChecker,
196 CK_NewDeleteLeaksChecker,
197 CK_MismatchedDeallocatorChecker,
198 CK_InnerPointerChecker,
199 CK_NumCheckKinds
200 };
201
202 enum class MemoryOperationKind {
203 MOK_Allocate,
204 MOK_Free,
205 MOK_Any
206 };
207
208 DefaultBool IsOptimistic;
209
210 DefaultBool ChecksEnabled[CK_NumCheckKinds];
211 CheckName CheckNames[CK_NumCheckKinds];
212
213 void checkPreCall(const CallEvent &Call, CheckerContext &C) const;
214 void checkPostStmt(const CallExpr *CE, CheckerContext &C) const;
215 void checkPostStmt(const CXXNewExpr *NE, CheckerContext &C) const;
216 void checkNewAllocator(const CXXNewExpr *NE, SVal Target,
217 CheckerContext &C) const;
218 void checkPreStmt(const CXXDeleteExpr *DE, CheckerContext &C) const;
219 void checkPostObjCMessage(const ObjCMethodCall &Call, CheckerContext &C) const;
220 void checkPostStmt(const BlockExpr *BE, CheckerContext &C) const;
221 void checkDeadSymbols(SymbolReaper &SymReaper, CheckerContext &C) const;
222 void checkPreStmt(const ReturnStmt *S, CheckerContext &C) const;
223 void checkEndFunction(const ReturnStmt *S, CheckerContext &C) const;
224 ProgramStateRef evalAssume(ProgramStateRef state, SVal Cond,
225 bool Assumption) const;
226 void checkLocation(SVal l, bool isLoad, const Stmt *S,
227 CheckerContext &C) const;
228
229 ProgramStateRef checkPointerEscape(ProgramStateRef State,
230 const InvalidatedSymbols &Escaped,
231 const CallEvent *Call,
232 PointerEscapeKind Kind) const;
233 ProgramStateRef checkConstPointerEscape(ProgramStateRef State,
234 const InvalidatedSymbols &Escaped,
235 const CallEvent *Call,
236 PointerEscapeKind Kind) const;
237
238 void printState(raw_ostream &Out, ProgramStateRef State,
239 const char *NL, const char *Sep) const override;
240
241 private:
242 mutable std::unique_ptr<BugType> BT_DoubleFree[CK_NumCheckKinds];
243 mutable std::unique_ptr<BugType> BT_DoubleDelete;
244 mutable std::unique_ptr<BugType> BT_Leak[CK_NumCheckKinds];
245 mutable std::unique_ptr<BugType> BT_UseFree[CK_NumCheckKinds];
246 mutable std::unique_ptr<BugType> BT_BadFree[CK_NumCheckKinds];
247 mutable std::unique_ptr<BugType> BT_FreeAlloca[CK_NumCheckKinds];
248 mutable std::unique_ptr<BugType> BT_MismatchedDealloc;
249 mutable std::unique_ptr<BugType> BT_OffsetFree[CK_NumCheckKinds];
250 mutable std::unique_ptr<BugType> BT_UseZerroAllocated[CK_NumCheckKinds];
251 mutable IdentifierInfo *II_alloca, *II_win_alloca, *II_malloc, *II_free,
252 *II_realloc, *II_calloc, *II_valloc, *II_reallocf,
253 *II_strndup, *II_strdup, *II_win_strdup, *II_kmalloc,
254 *II_kfree, *II_if_nameindex, *II_if_freenameindex,
255 *II_wcsdup, *II_win_wcsdup, *II_g_malloc,
256 *II_g_malloc0, *II_g_realloc, *II_g_try_malloc,
257 *II_g_try_malloc0, *II_g_try_realloc, *II_g_free,
258 *II_g_memdup, *II_g_malloc_n, *II_g_malloc0_n,
259 *II_g_realloc_n, *II_g_try_malloc_n,
260 *II_g_try_malloc0_n, *II_g_try_realloc_n;
261 mutable Optional<uint64_t> KernelZeroFlagVal;
262
263 void initIdentifierInfo(ASTContext &C) const;
264
265 /// Determine family of a deallocation expression.
266 AllocationFamily getAllocationFamily(CheckerContext &C, const Stmt *S) const;
267
268 /// Print names of allocators and deallocators.
269 ///
270 /// \returns true on success.
271 bool printAllocDeallocName(raw_ostream &os, CheckerContext &C,
272 const Expr *E) const;
273
274 /// Print expected name of an allocator based on the deallocator's
275 /// family derived from the DeallocExpr.
276 void printExpectedAllocName(raw_ostream &os, CheckerContext &C,
277 const Expr *DeallocExpr) const;
278 /// Print expected name of a deallocator based on the allocator's
279 /// family.
280 void printExpectedDeallocName(raw_ostream &os, AllocationFamily Family) const;
281
282 ///@{
283 /// Check if this is one of the functions which can allocate/reallocate memory
284 /// pointed to by one of its arguments.
285 bool isMemFunction(const FunctionDecl *FD, ASTContext &C) const;
286 bool isCMemFunction(const FunctionDecl *FD,
287 ASTContext &C,
288 AllocationFamily Family,
289 MemoryOperationKind MemKind) const;
290 bool isStandardNewDelete(const FunctionDecl *FD, ASTContext &C) const;
291 ///@}
292
293 /// Process C++ operator new()'s allocation, which is the part of C++
294 /// new-expression that goes before the constructor.
295 void processNewAllocation(const CXXNewExpr *NE, CheckerContext &C,
296 SVal Target) const;
297
298 /// Perform a zero-allocation check.
299 /// The optional \p RetVal parameter specifies the newly allocated pointer
300 /// value; if unspecified, the value of expression \p E is used.
301 ProgramStateRef ProcessZeroAllocation(CheckerContext &C, const Expr *E,
302 const unsigned AllocationSizeArg,
303 ProgramStateRef State,
304 Optional<SVal> RetVal = None) const;
305
306 ProgramStateRef MallocMemReturnsAttr(CheckerContext &C,
307 const CallExpr *CE,
308 const OwnershipAttr* Att,
309 ProgramStateRef State) const;
310 static ProgramStateRef MallocMemAux(CheckerContext &C, const CallExpr *CE,
311 const Expr *SizeEx, SVal Init,
312 ProgramStateRef State,
313 AllocationFamily Family = AF_Malloc);
314 static ProgramStateRef MallocMemAux(CheckerContext &C, const CallExpr *CE,
315 SVal SizeEx, SVal Init,
316 ProgramStateRef State,
317 AllocationFamily Family = AF_Malloc);
318
319 static ProgramStateRef addExtentSize(CheckerContext &C, const CXXNewExpr *NE,
320 ProgramStateRef State, SVal Target);
321
322 // Check if this malloc() for special flags. At present that means M_ZERO or
323 // __GFP_ZERO (in which case, treat it like calloc).
324 llvm::Optional<ProgramStateRef>
325 performKernelMalloc(const CallExpr *CE, CheckerContext &C,
326 const ProgramStateRef &State) const;
327
328 /// Update the RefState to reflect the new memory allocation.
329 /// The optional \p RetVal parameter specifies the newly allocated pointer
330 /// value; if unspecified, the value of expression \p E is used.
331 static ProgramStateRef
332 MallocUpdateRefState(CheckerContext &C, const Expr *E, ProgramStateRef State,
333 AllocationFamily Family = AF_Malloc,
334 Optional<SVal> RetVal = None);
335
336 ProgramStateRef FreeMemAttr(CheckerContext &C, const CallExpr *CE,
337 const OwnershipAttr* Att,
338 ProgramStateRef State) const;
339 ProgramStateRef FreeMemAux(CheckerContext &C, const CallExpr *CE,
340 ProgramStateRef state, unsigned Num,
341 bool Hold,
342 bool &ReleasedAllocated,
343 bool ReturnsNullOnFailure = false) const;
344 ProgramStateRef FreeMemAux(CheckerContext &C, const Expr *Arg,
345 const Expr *ParentExpr,
346 ProgramStateRef State,
347 bool Hold,
348 bool &ReleasedAllocated,
349 bool ReturnsNullOnFailure = false) const;
350
351 ProgramStateRef ReallocMemAux(CheckerContext &C, const CallExpr *CE,
352 bool FreesMemOnFailure,
353 ProgramStateRef State,
354 bool SuffixWithN = false) const;
355 static SVal evalMulForBufferSize(CheckerContext &C, const Expr *Blocks,
356 const Expr *BlockBytes);
357 static ProgramStateRef CallocMem(CheckerContext &C, const CallExpr *CE,
358 ProgramStateRef State);
359
360 /// Check if the memory associated with this symbol was released.
361 bool isReleased(SymbolRef Sym, CheckerContext &C) const;
362
363 /// See if deallocation happens in a suspicious context. If so, escape the
364 /// pointers that otherwise would have been deallocated and return true.
365 bool suppressDeallocationsInSuspiciousContexts(const CallExpr *CE,
366 CheckerContext &C) const;
367
368 bool checkUseAfterFree(SymbolRef Sym, CheckerContext &C, const Stmt *S) const;
369
370 void checkUseZeroAllocated(SymbolRef Sym, CheckerContext &C,
371 const Stmt *S) const;
372
373 bool checkDoubleDelete(SymbolRef Sym, CheckerContext &C) const;
374
375 /// Check if the function is known free memory, or if it is
376 /// "interesting" and should be modeled explicitly.
377 ///
378 /// \param [out] EscapingSymbol A function might not free memory in general,
379 /// but could be known to free a particular symbol. In this case, false is
380 /// returned and the single escaping symbol is returned through the out
381 /// parameter.
382 ///
383 /// We assume that pointers do not escape through calls to system functions
384 /// not handled by this checker.
385 bool mayFreeAnyEscapedMemoryOrIsModeledExplicitly(const CallEvent *Call,
386 ProgramStateRef State,
387 SymbolRef &EscapingSymbol) const;
388
389 // Implementation of the checkPointerEscape callbacks.
390 ProgramStateRef checkPointerEscapeAux(ProgramStateRef State,
391 const InvalidatedSymbols &Escaped,
392 const CallEvent *Call,
393 PointerEscapeKind Kind,
394 bool(*CheckRefState)(const RefState*)) const;
395
396 // Implementation of the checkPreStmt and checkEndFunction callbacks.
397 void checkEscapeOnReturn(const ReturnStmt *S, CheckerContext &C) const;
398
399 ///@{
400 /// Tells if a given family/call/symbol is tracked by the current checker.
401 /// Sets CheckKind to the kind of the checker responsible for this
402 /// family/call/symbol.
403 Optional<CheckKind> getCheckIfTracked(AllocationFamily Family,
404 bool IsALeakCheck = false) const;
405 Optional<CheckKind> getCheckIfTracked(CheckerContext &C,
406 const Stmt *AllocDeallocStmt,
407 bool IsALeakCheck = false) const;
408 Optional<CheckKind> getCheckIfTracked(CheckerContext &C, SymbolRef Sym,
409 bool IsALeakCheck = false) const;
410 ///@}
411 static bool SummarizeValue(raw_ostream &os, SVal V);
412 static bool SummarizeRegion(raw_ostream &os, const MemRegion *MR);
413 void ReportBadFree(CheckerContext &C, SVal ArgVal, SourceRange Range,
414 const Expr *DeallocExpr) const;
415 void ReportFreeAlloca(CheckerContext &C, SVal ArgVal,
416 SourceRange Range) const;
417 void ReportMismatchedDealloc(CheckerContext &C, SourceRange Range,
418 const Expr *DeallocExpr, const RefState *RS,
419 SymbolRef Sym, bool OwnershipTransferred) const;
420 void ReportOffsetFree(CheckerContext &C, SVal ArgVal, SourceRange Range,
421 const Expr *DeallocExpr,
422 const Expr *AllocExpr = nullptr) const;
423 void ReportUseAfterFree(CheckerContext &C, SourceRange Range,
424 SymbolRef Sym) const;
425 void ReportDoubleFree(CheckerContext &C, SourceRange Range, bool Released,
426 SymbolRef Sym, SymbolRef PrevSym) const;
427
428 void ReportDoubleDelete(CheckerContext &C, SymbolRef Sym) const;
429
430 void ReportUseZeroAllocated(CheckerContext &C, SourceRange Range,
431 SymbolRef Sym) const;
432
433 void ReportFunctionPointerFree(CheckerContext &C, SVal ArgVal,
434 SourceRange Range, const Expr *FreeExpr) const;
435
436 /// Find the location of the allocation for Sym on the path leading to the
437 /// exploded node N.
438 LeakInfo getAllocationSite(const ExplodedNode *N, SymbolRef Sym,
439 CheckerContext &C) const;
440
441 void reportLeak(SymbolRef Sym, ExplodedNode *N, CheckerContext &C) const;
442
443 /// The bug visitor which allows us to print extra diagnostics along the
444 /// BugReport path. For example, showing the allocation site of the leaked
445 /// region.
446 class MallocBugVisitor final : public BugReporterVisitor {
447 protected:
448 enum NotificationMode {
449 Normal,
450 ReallocationFailed
451 };
452
453 // The allocated region symbol tracked by the main analysis.
454 SymbolRef Sym;
455
456 // The mode we are in, i.e. what kind of diagnostics will be emitted.
457 NotificationMode Mode;
458
459 // A symbol from when the primary region should have been reallocated.
460 SymbolRef FailedReallocSymbol;
461
462 // A C++ destructor stack frame in which memory was released. Used for
463 // miscellaneous false positive suppression.
464 const StackFrameContext *ReleaseDestructorLC;
465
466 bool IsLeak;
467
468 public:
MallocBugVisitor(SymbolRef S,bool isLeak=false)469 MallocBugVisitor(SymbolRef S, bool isLeak = false)
470 : Sym(S), Mode(Normal), FailedReallocSymbol(nullptr),
471 ReleaseDestructorLC(nullptr), IsLeak(isLeak) {}
472
getTag()473 static void *getTag() {
474 static int Tag = 0;
475 return &Tag;
476 }
477
Profile(llvm::FoldingSetNodeID & ID) const478 void Profile(llvm::FoldingSetNodeID &ID) const override {
479 ID.AddPointer(getTag());
480 ID.AddPointer(Sym);
481 }
482
isAllocated(const RefState * S,const RefState * SPrev,const Stmt * Stmt)483 inline bool isAllocated(const RefState *S, const RefState *SPrev,
484 const Stmt *Stmt) {
485 // Did not track -> allocated. Other state (released) -> allocated.
486 return (Stmt && (isa<CallExpr>(Stmt) || isa<CXXNewExpr>(Stmt)) &&
487 (S && (S->isAllocated() || S->isAllocatedOfSizeZero())) &&
488 (!SPrev || !(SPrev->isAllocated() ||
489 SPrev->isAllocatedOfSizeZero())));
490 }
491
isReleased(const RefState * S,const RefState * SPrev,const Stmt * Stmt)492 inline bool isReleased(const RefState *S, const RefState *SPrev,
493 const Stmt *Stmt) {
494 // Did not track -> released. Other state (allocated) -> released.
495 // The statement associated with the release might be missing.
496 bool IsReleased = (S && S->isReleased()) &&
497 (!SPrev || !SPrev->isReleased());
498 assert(!IsReleased ||
499 (Stmt && (isa<CallExpr>(Stmt) || isa<CXXDeleteExpr>(Stmt))) ||
500 (!Stmt && S->getAllocationFamily() == AF_InnerBuffer));
501 return IsReleased;
502 }
503
isRelinquished(const RefState * S,const RefState * SPrev,const Stmt * Stmt)504 inline bool isRelinquished(const RefState *S, const RefState *SPrev,
505 const Stmt *Stmt) {
506 // Did not track -> relinquished. Other state (allocated) -> relinquished.
507 return (Stmt && (isa<CallExpr>(Stmt) || isa<ObjCMessageExpr>(Stmt) ||
508 isa<ObjCPropertyRefExpr>(Stmt)) &&
509 (S && S->isRelinquished()) &&
510 (!SPrev || !SPrev->isRelinquished()));
511 }
512
isReallocFailedCheck(const RefState * S,const RefState * SPrev,const Stmt * Stmt)513 inline bool isReallocFailedCheck(const RefState *S, const RefState *SPrev,
514 const Stmt *Stmt) {
515 // If the expression is not a call, and the state change is
516 // released -> allocated, it must be the realloc return value
517 // check. If we have to handle more cases here, it might be cleaner just
518 // to track this extra bit in the state itself.
519 return ((!Stmt || !isa<CallExpr>(Stmt)) &&
520 (S && (S->isAllocated() || S->isAllocatedOfSizeZero())) &&
521 (SPrev && !(SPrev->isAllocated() ||
522 SPrev->isAllocatedOfSizeZero())));
523 }
524
525 std::shared_ptr<PathDiagnosticPiece> VisitNode(const ExplodedNode *N,
526 BugReporterContext &BRC,
527 BugReport &BR) override;
528
529 std::shared_ptr<PathDiagnosticPiece>
getEndPath(BugReporterContext & BRC,const ExplodedNode * EndPathNode,BugReport & BR)530 getEndPath(BugReporterContext &BRC, const ExplodedNode *EndPathNode,
531 BugReport &BR) override {
532 if (!IsLeak)
533 return nullptr;
534
535 PathDiagnosticLocation L =
536 PathDiagnosticLocation::createEndOfPath(EndPathNode,
537 BRC.getSourceManager());
538 // Do not add the statement itself as a range in case of leak.
539 return std::make_shared<PathDiagnosticEventPiece>(L, BR.getDescription(),
540 false);
541 }
542
543 private:
544 class StackHintGeneratorForReallocationFailed
545 : public StackHintGeneratorForSymbol {
546 public:
StackHintGeneratorForReallocationFailed(SymbolRef S,StringRef M)547 StackHintGeneratorForReallocationFailed(SymbolRef S, StringRef M)
548 : StackHintGeneratorForSymbol(S, M) {}
549
getMessageForArg(const Expr * ArgE,unsigned ArgIndex)550 std::string getMessageForArg(const Expr *ArgE,
551 unsigned ArgIndex) override {
552 // Printed parameters start at 1, not 0.
553 ++ArgIndex;
554
555 SmallString<200> buf;
556 llvm::raw_svector_ostream os(buf);
557
558 os << "Reallocation of " << ArgIndex << llvm::getOrdinalSuffix(ArgIndex)
559 << " parameter failed";
560
561 return os.str();
562 }
563
getMessageForReturn(const CallExpr * CallExpr)564 std::string getMessageForReturn(const CallExpr *CallExpr) override {
565 return "Reallocation of returned value failed";
566 }
567 };
568 };
569 };
570 } // end anonymous namespace
571
572 REGISTER_MAP_WITH_PROGRAMSTATE(RegionState, SymbolRef, RefState)
573 REGISTER_MAP_WITH_PROGRAMSTATE(ReallocPairs, SymbolRef, ReallocPair)
574 REGISTER_SET_WITH_PROGRAMSTATE(ReallocSizeZeroSymbols, SymbolRef)
575
576 // A map from the freed symbol to the symbol representing the return value of
577 // the free function.
578 REGISTER_MAP_WITH_PROGRAMSTATE(FreeReturnValue, SymbolRef, SymbolRef)
579
580 namespace {
581 class StopTrackingCallback final : public SymbolVisitor {
582 ProgramStateRef state;
583 public:
StopTrackingCallback(ProgramStateRef st)584 StopTrackingCallback(ProgramStateRef st) : state(std::move(st)) {}
getState() const585 ProgramStateRef getState() const { return state; }
586
VisitSymbol(SymbolRef sym)587 bool VisitSymbol(SymbolRef sym) override {
588 state = state->remove<RegionState>(sym);
589 return true;
590 }
591 };
592 } // end anonymous namespace
593
initIdentifierInfo(ASTContext & Ctx) const594 void MallocChecker::initIdentifierInfo(ASTContext &Ctx) const {
595 if (II_malloc)
596 return;
597 II_alloca = &Ctx.Idents.get("alloca");
598 II_malloc = &Ctx.Idents.get("malloc");
599 II_free = &Ctx.Idents.get("free");
600 II_realloc = &Ctx.Idents.get("realloc");
601 II_reallocf = &Ctx.Idents.get("reallocf");
602 II_calloc = &Ctx.Idents.get("calloc");
603 II_valloc = &Ctx.Idents.get("valloc");
604 II_strdup = &Ctx.Idents.get("strdup");
605 II_strndup = &Ctx.Idents.get("strndup");
606 II_wcsdup = &Ctx.Idents.get("wcsdup");
607 II_kmalloc = &Ctx.Idents.get("kmalloc");
608 II_kfree = &Ctx.Idents.get("kfree");
609 II_if_nameindex = &Ctx.Idents.get("if_nameindex");
610 II_if_freenameindex = &Ctx.Idents.get("if_freenameindex");
611
612 //MSVC uses `_`-prefixed instead, so we check for them too.
613 II_win_strdup = &Ctx.Idents.get("_strdup");
614 II_win_wcsdup = &Ctx.Idents.get("_wcsdup");
615 II_win_alloca = &Ctx.Idents.get("_alloca");
616
617 // Glib
618 II_g_malloc = &Ctx.Idents.get("g_malloc");
619 II_g_malloc0 = &Ctx.Idents.get("g_malloc0");
620 II_g_realloc = &Ctx.Idents.get("g_realloc");
621 II_g_try_malloc = &Ctx.Idents.get("g_try_malloc");
622 II_g_try_malloc0 = &Ctx.Idents.get("g_try_malloc0");
623 II_g_try_realloc = &Ctx.Idents.get("g_try_realloc");
624 II_g_free = &Ctx.Idents.get("g_free");
625 II_g_memdup = &Ctx.Idents.get("g_memdup");
626 II_g_malloc_n = &Ctx.Idents.get("g_malloc_n");
627 II_g_malloc0_n = &Ctx.Idents.get("g_malloc0_n");
628 II_g_realloc_n = &Ctx.Idents.get("g_realloc_n");
629 II_g_try_malloc_n = &Ctx.Idents.get("g_try_malloc_n");
630 II_g_try_malloc0_n = &Ctx.Idents.get("g_try_malloc0_n");
631 II_g_try_realloc_n = &Ctx.Idents.get("g_try_realloc_n");
632 }
633
isMemFunction(const FunctionDecl * FD,ASTContext & C) const634 bool MallocChecker::isMemFunction(const FunctionDecl *FD, ASTContext &C) const {
635 if (isCMemFunction(FD, C, AF_Malloc, MemoryOperationKind::MOK_Any))
636 return true;
637
638 if (isCMemFunction(FD, C, AF_IfNameIndex, MemoryOperationKind::MOK_Any))
639 return true;
640
641 if (isCMemFunction(FD, C, AF_Alloca, MemoryOperationKind::MOK_Any))
642 return true;
643
644 if (isStandardNewDelete(FD, C))
645 return true;
646
647 return false;
648 }
649
isCMemFunction(const FunctionDecl * FD,ASTContext & C,AllocationFamily Family,MemoryOperationKind MemKind) const650 bool MallocChecker::isCMemFunction(const FunctionDecl *FD,
651 ASTContext &C,
652 AllocationFamily Family,
653 MemoryOperationKind MemKind) const {
654 if (!FD)
655 return false;
656
657 bool CheckFree = (MemKind == MemoryOperationKind::MOK_Any ||
658 MemKind == MemoryOperationKind::MOK_Free);
659 bool CheckAlloc = (MemKind == MemoryOperationKind::MOK_Any ||
660 MemKind == MemoryOperationKind::MOK_Allocate);
661
662 if (FD->getKind() == Decl::Function) {
663 const IdentifierInfo *FunI = FD->getIdentifier();
664 initIdentifierInfo(C);
665
666 if (Family == AF_Malloc && CheckFree) {
667 if (FunI == II_free || FunI == II_realloc || FunI == II_reallocf ||
668 FunI == II_g_free || FunI == II_kfree)
669 return true;
670 }
671
672 if (Family == AF_Malloc && CheckAlloc) {
673 if (FunI == II_malloc || FunI == II_realloc || FunI == II_reallocf ||
674 FunI == II_calloc || FunI == II_valloc || FunI == II_strdup ||
675 FunI == II_win_strdup || FunI == II_strndup || FunI == II_wcsdup ||
676 FunI == II_win_wcsdup || FunI == II_kmalloc ||
677 FunI == II_g_malloc || FunI == II_g_malloc0 ||
678 FunI == II_g_realloc || FunI == II_g_try_malloc ||
679 FunI == II_g_try_malloc0 || FunI == II_g_try_realloc ||
680 FunI == II_g_memdup || FunI == II_g_malloc_n ||
681 FunI == II_g_malloc0_n || FunI == II_g_realloc_n ||
682 FunI == II_g_try_malloc_n || FunI == II_g_try_malloc0_n ||
683 FunI == II_g_try_realloc_n)
684 return true;
685 }
686
687 if (Family == AF_IfNameIndex && CheckFree) {
688 if (FunI == II_if_freenameindex)
689 return true;
690 }
691
692 if (Family == AF_IfNameIndex && CheckAlloc) {
693 if (FunI == II_if_nameindex)
694 return true;
695 }
696
697 if (Family == AF_Alloca && CheckAlloc) {
698 if (FunI == II_alloca || FunI == II_win_alloca)
699 return true;
700 }
701 }
702
703 if (Family != AF_Malloc)
704 return false;
705
706 if (IsOptimistic && FD->hasAttrs()) {
707 for (const auto *I : FD->specific_attrs<OwnershipAttr>()) {
708 OwnershipAttr::OwnershipKind OwnKind = I->getOwnKind();
709 if(OwnKind == OwnershipAttr::Takes || OwnKind == OwnershipAttr::Holds) {
710 if (CheckFree)
711 return true;
712 } else if (OwnKind == OwnershipAttr::Returns) {
713 if (CheckAlloc)
714 return true;
715 }
716 }
717 }
718
719 return false;
720 }
721
722 // Tells if the callee is one of the builtin new/delete operators, including
723 // placement operators and other standard overloads.
isStandardNewDelete(const FunctionDecl * FD,ASTContext & C) const724 bool MallocChecker::isStandardNewDelete(const FunctionDecl *FD,
725 ASTContext &C) const {
726 if (!FD)
727 return false;
728
729 OverloadedOperatorKind Kind = FD->getOverloadedOperator();
730 if (Kind != OO_New && Kind != OO_Array_New &&
731 Kind != OO_Delete && Kind != OO_Array_Delete)
732 return false;
733
734 // This is standard if and only if it's not defined in a user file.
735 SourceLocation L = FD->getLocation();
736 // If the header for operator delete is not included, it's still defined
737 // in an invalid source location. Check to make sure we don't crash.
738 return !L.isValid() || C.getSourceManager().isInSystemHeader(L);
739 }
740
performKernelMalloc(const CallExpr * CE,CheckerContext & C,const ProgramStateRef & State) const741 llvm::Optional<ProgramStateRef> MallocChecker::performKernelMalloc(
742 const CallExpr *CE, CheckerContext &C, const ProgramStateRef &State) const {
743 // 3-argument malloc(), as commonly used in {Free,Net,Open}BSD Kernels:
744 //
745 // void *malloc(unsigned long size, struct malloc_type *mtp, int flags);
746 //
747 // One of the possible flags is M_ZERO, which means 'give me back an
748 // allocation which is already zeroed', like calloc.
749
750 // 2-argument kmalloc(), as used in the Linux kernel:
751 //
752 // void *kmalloc(size_t size, gfp_t flags);
753 //
754 // Has the similar flag value __GFP_ZERO.
755
756 // This logic is largely cloned from O_CREAT in UnixAPIChecker, maybe some
757 // code could be shared.
758
759 ASTContext &Ctx = C.getASTContext();
760 llvm::Triple::OSType OS = Ctx.getTargetInfo().getTriple().getOS();
761
762 if (!KernelZeroFlagVal.hasValue()) {
763 if (OS == llvm::Triple::FreeBSD)
764 KernelZeroFlagVal = 0x0100;
765 else if (OS == llvm::Triple::NetBSD)
766 KernelZeroFlagVal = 0x0002;
767 else if (OS == llvm::Triple::OpenBSD)
768 KernelZeroFlagVal = 0x0008;
769 else if (OS == llvm::Triple::Linux)
770 // __GFP_ZERO
771 KernelZeroFlagVal = 0x8000;
772 else
773 // FIXME: We need a more general way of getting the M_ZERO value.
774 // See also: O_CREAT in UnixAPIChecker.cpp.
775
776 // Fall back to normal malloc behavior on platforms where we don't
777 // know M_ZERO.
778 return None;
779 }
780
781 // We treat the last argument as the flags argument, and callers fall-back to
782 // normal malloc on a None return. This works for the FreeBSD kernel malloc
783 // as well as Linux kmalloc.
784 if (CE->getNumArgs() < 2)
785 return None;
786
787 const Expr *FlagsEx = CE->getArg(CE->getNumArgs() - 1);
788 const SVal V = C.getSVal(FlagsEx);
789 if (!V.getAs<NonLoc>()) {
790 // The case where 'V' can be a location can only be due to a bad header,
791 // so in this case bail out.
792 return None;
793 }
794
795 NonLoc Flags = V.castAs<NonLoc>();
796 NonLoc ZeroFlag = C.getSValBuilder()
797 .makeIntVal(KernelZeroFlagVal.getValue(), FlagsEx->getType())
798 .castAs<NonLoc>();
799 SVal MaskedFlagsUC = C.getSValBuilder().evalBinOpNN(State, BO_And,
800 Flags, ZeroFlag,
801 FlagsEx->getType());
802 if (MaskedFlagsUC.isUnknownOrUndef())
803 return None;
804 DefinedSVal MaskedFlags = MaskedFlagsUC.castAs<DefinedSVal>();
805
806 // Check if maskedFlags is non-zero.
807 ProgramStateRef TrueState, FalseState;
808 std::tie(TrueState, FalseState) = State->assume(MaskedFlags);
809
810 // If M_ZERO is set, treat this like calloc (initialized).
811 if (TrueState && !FalseState) {
812 SVal ZeroVal = C.getSValBuilder().makeZeroVal(Ctx.CharTy);
813 return MallocMemAux(C, CE, CE->getArg(0), ZeroVal, TrueState);
814 }
815
816 return None;
817 }
818
evalMulForBufferSize(CheckerContext & C,const Expr * Blocks,const Expr * BlockBytes)819 SVal MallocChecker::evalMulForBufferSize(CheckerContext &C, const Expr *Blocks,
820 const Expr *BlockBytes) {
821 SValBuilder &SB = C.getSValBuilder();
822 SVal BlocksVal = C.getSVal(Blocks);
823 SVal BlockBytesVal = C.getSVal(BlockBytes);
824 ProgramStateRef State = C.getState();
825 SVal TotalSize = SB.evalBinOp(State, BO_Mul, BlocksVal, BlockBytesVal,
826 SB.getContext().getSizeType());
827 return TotalSize;
828 }
829
checkPostStmt(const CallExpr * CE,CheckerContext & C) const830 void MallocChecker::checkPostStmt(const CallExpr *CE, CheckerContext &C) const {
831 if (C.wasInlined)
832 return;
833
834 const FunctionDecl *FD = C.getCalleeDecl(CE);
835 if (!FD)
836 return;
837
838 ProgramStateRef State = C.getState();
839 bool ReleasedAllocatedMemory = false;
840
841 if (FD->getKind() == Decl::Function) {
842 initIdentifierInfo(C.getASTContext());
843 IdentifierInfo *FunI = FD->getIdentifier();
844
845 if (FunI == II_malloc || FunI == II_g_malloc || FunI == II_g_try_malloc) {
846 if (CE->getNumArgs() < 1)
847 return;
848 if (CE->getNumArgs() < 3) {
849 State = MallocMemAux(C, CE, CE->getArg(0), UndefinedVal(), State);
850 if (CE->getNumArgs() == 1)
851 State = ProcessZeroAllocation(C, CE, 0, State);
852 } else if (CE->getNumArgs() == 3) {
853 llvm::Optional<ProgramStateRef> MaybeState =
854 performKernelMalloc(CE, C, State);
855 if (MaybeState.hasValue())
856 State = MaybeState.getValue();
857 else
858 State = MallocMemAux(C, CE, CE->getArg(0), UndefinedVal(), State);
859 }
860 } else if (FunI == II_kmalloc) {
861 if (CE->getNumArgs() < 1)
862 return;
863 llvm::Optional<ProgramStateRef> MaybeState =
864 performKernelMalloc(CE, C, State);
865 if (MaybeState.hasValue())
866 State = MaybeState.getValue();
867 else
868 State = MallocMemAux(C, CE, CE->getArg(0), UndefinedVal(), State);
869 } else if (FunI == II_valloc) {
870 if (CE->getNumArgs() < 1)
871 return;
872 State = MallocMemAux(C, CE, CE->getArg(0), UndefinedVal(), State);
873 State = ProcessZeroAllocation(C, CE, 0, State);
874 } else if (FunI == II_realloc || FunI == II_g_realloc ||
875 FunI == II_g_try_realloc) {
876 State = ReallocMemAux(C, CE, false, State);
877 State = ProcessZeroAllocation(C, CE, 1, State);
878 } else if (FunI == II_reallocf) {
879 State = ReallocMemAux(C, CE, true, State);
880 State = ProcessZeroAllocation(C, CE, 1, State);
881 } else if (FunI == II_calloc) {
882 State = CallocMem(C, CE, State);
883 State = ProcessZeroAllocation(C, CE, 0, State);
884 State = ProcessZeroAllocation(C, CE, 1, State);
885 } else if (FunI == II_free || FunI == II_g_free || FunI == II_kfree) {
886 if (suppressDeallocationsInSuspiciousContexts(CE, C))
887 return;
888
889 State = FreeMemAux(C, CE, State, 0, false, ReleasedAllocatedMemory);
890 } else if (FunI == II_strdup || FunI == II_win_strdup ||
891 FunI == II_wcsdup || FunI == II_win_wcsdup) {
892 State = MallocUpdateRefState(C, CE, State);
893 } else if (FunI == II_strndup) {
894 State = MallocUpdateRefState(C, CE, State);
895 } else if (FunI == II_alloca || FunI == II_win_alloca) {
896 if (CE->getNumArgs() < 1)
897 return;
898 State = MallocMemAux(C, CE, CE->getArg(0), UndefinedVal(), State,
899 AF_Alloca);
900 State = ProcessZeroAllocation(C, CE, 0, State);
901 } else if (isStandardNewDelete(FD, C.getASTContext())) {
902 // Process direct calls to operator new/new[]/delete/delete[] functions
903 // as distinct from new/new[]/delete/delete[] expressions that are
904 // processed by the checkPostStmt callbacks for CXXNewExpr and
905 // CXXDeleteExpr.
906 OverloadedOperatorKind K = FD->getOverloadedOperator();
907 if (K == OO_New) {
908 State = MallocMemAux(C, CE, CE->getArg(0), UndefinedVal(), State,
909 AF_CXXNew);
910 State = ProcessZeroAllocation(C, CE, 0, State);
911 }
912 else if (K == OO_Array_New) {
913 State = MallocMemAux(C, CE, CE->getArg(0), UndefinedVal(), State,
914 AF_CXXNewArray);
915 State = ProcessZeroAllocation(C, CE, 0, State);
916 }
917 else if (K == OO_Delete || K == OO_Array_Delete)
918 State = FreeMemAux(C, CE, State, 0, false, ReleasedAllocatedMemory);
919 else
920 llvm_unreachable("not a new/delete operator");
921 } else if (FunI == II_if_nameindex) {
922 // Should we model this differently? We can allocate a fixed number of
923 // elements with zeros in the last one.
924 State = MallocMemAux(C, CE, UnknownVal(), UnknownVal(), State,
925 AF_IfNameIndex);
926 } else if (FunI == II_if_freenameindex) {
927 State = FreeMemAux(C, CE, State, 0, false, ReleasedAllocatedMemory);
928 } else if (FunI == II_g_malloc0 || FunI == II_g_try_malloc0) {
929 if (CE->getNumArgs() < 1)
930 return;
931 SValBuilder &svalBuilder = C.getSValBuilder();
932 SVal zeroVal = svalBuilder.makeZeroVal(svalBuilder.getContext().CharTy);
933 State = MallocMemAux(C, CE, CE->getArg(0), zeroVal, State);
934 State = ProcessZeroAllocation(C, CE, 0, State);
935 } else if (FunI == II_g_memdup) {
936 if (CE->getNumArgs() < 2)
937 return;
938 State = MallocMemAux(C, CE, CE->getArg(1), UndefinedVal(), State);
939 State = ProcessZeroAllocation(C, CE, 1, State);
940 } else if (FunI == II_g_malloc_n || FunI == II_g_try_malloc_n ||
941 FunI == II_g_malloc0_n || FunI == II_g_try_malloc0_n) {
942 if (CE->getNumArgs() < 2)
943 return;
944 SVal Init = UndefinedVal();
945 if (FunI == II_g_malloc0_n || FunI == II_g_try_malloc0_n) {
946 SValBuilder &SB = C.getSValBuilder();
947 Init = SB.makeZeroVal(SB.getContext().CharTy);
948 }
949 SVal TotalSize = evalMulForBufferSize(C, CE->getArg(0), CE->getArg(1));
950 State = MallocMemAux(C, CE, TotalSize, Init, State);
951 State = ProcessZeroAllocation(C, CE, 0, State);
952 State = ProcessZeroAllocation(C, CE, 1, State);
953 } else if (FunI == II_g_realloc_n || FunI == II_g_try_realloc_n) {
954 if (CE->getNumArgs() < 3)
955 return;
956 State = ReallocMemAux(C, CE, false, State, true);
957 State = ProcessZeroAllocation(C, CE, 1, State);
958 State = ProcessZeroAllocation(C, CE, 2, State);
959 }
960 }
961
962 if (IsOptimistic || ChecksEnabled[CK_MismatchedDeallocatorChecker]) {
963 // Check all the attributes, if there are any.
964 // There can be multiple of these attributes.
965 if (FD->hasAttrs())
966 for (const auto *I : FD->specific_attrs<OwnershipAttr>()) {
967 switch (I->getOwnKind()) {
968 case OwnershipAttr::Returns:
969 State = MallocMemReturnsAttr(C, CE, I, State);
970 break;
971 case OwnershipAttr::Takes:
972 case OwnershipAttr::Holds:
973 State = FreeMemAttr(C, CE, I, State);
974 break;
975 }
976 }
977 }
978 C.addTransition(State);
979 }
980
981 // Performs a 0-sized allocations check.
ProcessZeroAllocation(CheckerContext & C,const Expr * E,const unsigned AllocationSizeArg,ProgramStateRef State,Optional<SVal> RetVal) const982 ProgramStateRef MallocChecker::ProcessZeroAllocation(
983 CheckerContext &C, const Expr *E, const unsigned AllocationSizeArg,
984 ProgramStateRef State, Optional<SVal> RetVal) const {
985 if (!State)
986 return nullptr;
987
988 if (!RetVal)
989 RetVal = C.getSVal(E);
990
991 const Expr *Arg = nullptr;
992
993 if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
994 Arg = CE->getArg(AllocationSizeArg);
995 }
996 else if (const CXXNewExpr *NE = dyn_cast<CXXNewExpr>(E)) {
997 if (NE->isArray())
998 Arg = *NE->getArraySize();
999 else
1000 return State;
1001 }
1002 else
1003 llvm_unreachable("not a CallExpr or CXXNewExpr");
1004
1005 assert(Arg);
1006
1007 Optional<DefinedSVal> DefArgVal = C.getSVal(Arg).getAs<DefinedSVal>();
1008
1009 if (!DefArgVal)
1010 return State;
1011
1012 // Check if the allocation size is 0.
1013 ProgramStateRef TrueState, FalseState;
1014 SValBuilder &SvalBuilder = C.getSValBuilder();
1015 DefinedSVal Zero =
1016 SvalBuilder.makeZeroVal(Arg->getType()).castAs<DefinedSVal>();
1017
1018 std::tie(TrueState, FalseState) =
1019 State->assume(SvalBuilder.evalEQ(State, *DefArgVal, Zero));
1020
1021 if (TrueState && !FalseState) {
1022 SymbolRef Sym = RetVal->getAsLocSymbol();
1023 if (!Sym)
1024 return State;
1025
1026 const RefState *RS = State->get<RegionState>(Sym);
1027 if (RS) {
1028 if (RS->isAllocated())
1029 return TrueState->set<RegionState>(Sym,
1030 RefState::getAllocatedOfSizeZero(RS));
1031 else
1032 return State;
1033 } else {
1034 // Case of zero-size realloc. Historically 'realloc(ptr, 0)' is treated as
1035 // 'free(ptr)' and the returned value from 'realloc(ptr, 0)' is not
1036 // tracked. Add zero-reallocated Sym to the state to catch references
1037 // to zero-allocated memory.
1038 return TrueState->add<ReallocSizeZeroSymbols>(Sym);
1039 }
1040 }
1041
1042 // Assume the value is non-zero going forward.
1043 assert(FalseState);
1044 return FalseState;
1045 }
1046
getDeepPointeeType(QualType T)1047 static QualType getDeepPointeeType(QualType T) {
1048 QualType Result = T, PointeeType = T->getPointeeType();
1049 while (!PointeeType.isNull()) {
1050 Result = PointeeType;
1051 PointeeType = PointeeType->getPointeeType();
1052 }
1053 return Result;
1054 }
1055
treatUnusedNewEscaped(const CXXNewExpr * NE)1056 static bool treatUnusedNewEscaped(const CXXNewExpr *NE) {
1057
1058 const CXXConstructExpr *ConstructE = NE->getConstructExpr();
1059 if (!ConstructE)
1060 return false;
1061
1062 if (!NE->getAllocatedType()->getAsCXXRecordDecl())
1063 return false;
1064
1065 const CXXConstructorDecl *CtorD = ConstructE->getConstructor();
1066
1067 // Iterate over the constructor parameters.
1068 for (const auto *CtorParam : CtorD->parameters()) {
1069
1070 QualType CtorParamPointeeT = CtorParam->getType()->getPointeeType();
1071 if (CtorParamPointeeT.isNull())
1072 continue;
1073
1074 CtorParamPointeeT = getDeepPointeeType(CtorParamPointeeT);
1075
1076 if (CtorParamPointeeT->getAsCXXRecordDecl())
1077 return true;
1078 }
1079
1080 return false;
1081 }
1082
processNewAllocation(const CXXNewExpr * NE,CheckerContext & C,SVal Target) const1083 void MallocChecker::processNewAllocation(const CXXNewExpr *NE,
1084 CheckerContext &C,
1085 SVal Target) const {
1086 if (!isStandardNewDelete(NE->getOperatorNew(), C.getASTContext()))
1087 return;
1088
1089 ParentMap &PM = C.getLocationContext()->getParentMap();
1090 if (!PM.isConsumedExpr(NE) && treatUnusedNewEscaped(NE))
1091 return;
1092
1093 ProgramStateRef State = C.getState();
1094 // The return value from operator new is bound to a specified initialization
1095 // value (if any) and we don't want to loose this value. So we call
1096 // MallocUpdateRefState() instead of MallocMemAux() which breaks the
1097 // existing binding.
1098 State = MallocUpdateRefState(C, NE, State, NE->isArray() ? AF_CXXNewArray
1099 : AF_CXXNew, Target);
1100 State = addExtentSize(C, NE, State, Target);
1101 State = ProcessZeroAllocation(C, NE, 0, State, Target);
1102 C.addTransition(State);
1103 }
1104
checkPostStmt(const CXXNewExpr * NE,CheckerContext & C) const1105 void MallocChecker::checkPostStmt(const CXXNewExpr *NE,
1106 CheckerContext &C) const {
1107 if (!C.getAnalysisManager().getAnalyzerOptions().MayInlineCXXAllocator)
1108 processNewAllocation(NE, C, C.getSVal(NE));
1109 }
1110
checkNewAllocator(const CXXNewExpr * NE,SVal Target,CheckerContext & C) const1111 void MallocChecker::checkNewAllocator(const CXXNewExpr *NE, SVal Target,
1112 CheckerContext &C) const {
1113 if (!C.wasInlined)
1114 processNewAllocation(NE, C, Target);
1115 }
1116
1117 // Sets the extent value of the MemRegion allocated by
1118 // new expression NE to its size in Bytes.
1119 //
addExtentSize(CheckerContext & C,const CXXNewExpr * NE,ProgramStateRef State,SVal Target)1120 ProgramStateRef MallocChecker::addExtentSize(CheckerContext &C,
1121 const CXXNewExpr *NE,
1122 ProgramStateRef State,
1123 SVal Target) {
1124 if (!State)
1125 return nullptr;
1126 SValBuilder &svalBuilder = C.getSValBuilder();
1127 SVal ElementCount;
1128 const SubRegion *Region;
1129 if (NE->isArray()) {
1130 const Expr *SizeExpr = *NE->getArraySize();
1131 ElementCount = C.getSVal(SizeExpr);
1132 // Store the extent size for the (symbolic)region
1133 // containing the elements.
1134 Region = Target.getAsRegion()
1135 ->getAs<SubRegion>()
1136 ->StripCasts()
1137 ->getAs<SubRegion>();
1138 } else {
1139 ElementCount = svalBuilder.makeIntVal(1, true);
1140 Region = Target.getAsRegion()->getAs<SubRegion>();
1141 }
1142 assert(Region);
1143
1144 // Set the region's extent equal to the Size in Bytes.
1145 QualType ElementType = NE->getAllocatedType();
1146 ASTContext &AstContext = C.getASTContext();
1147 CharUnits TypeSize = AstContext.getTypeSizeInChars(ElementType);
1148
1149 if (ElementCount.getAs<NonLoc>()) {
1150 DefinedOrUnknownSVal Extent = Region->getExtent(svalBuilder);
1151 // size in Bytes = ElementCount*TypeSize
1152 SVal SizeInBytes = svalBuilder.evalBinOpNN(
1153 State, BO_Mul, ElementCount.castAs<NonLoc>(),
1154 svalBuilder.makeArrayIndex(TypeSize.getQuantity()),
1155 svalBuilder.getArrayIndexType());
1156 DefinedOrUnknownSVal extentMatchesSize = svalBuilder.evalEQ(
1157 State, Extent, SizeInBytes.castAs<DefinedOrUnknownSVal>());
1158 State = State->assume(extentMatchesSize, true);
1159 }
1160 return State;
1161 }
1162
checkPreStmt(const CXXDeleteExpr * DE,CheckerContext & C) const1163 void MallocChecker::checkPreStmt(const CXXDeleteExpr *DE,
1164 CheckerContext &C) const {
1165
1166 if (!ChecksEnabled[CK_NewDeleteChecker])
1167 if (SymbolRef Sym = C.getSVal(DE->getArgument()).getAsSymbol())
1168 checkUseAfterFree(Sym, C, DE->getArgument());
1169
1170 if (!isStandardNewDelete(DE->getOperatorDelete(), C.getASTContext()))
1171 return;
1172
1173 ProgramStateRef State = C.getState();
1174 bool ReleasedAllocated;
1175 State = FreeMemAux(C, DE->getArgument(), DE, State,
1176 /*Hold*/false, ReleasedAllocated);
1177
1178 C.addTransition(State);
1179 }
1180
isKnownDeallocObjCMethodName(const ObjCMethodCall & Call)1181 static bool isKnownDeallocObjCMethodName(const ObjCMethodCall &Call) {
1182 // If the first selector piece is one of the names below, assume that the
1183 // object takes ownership of the memory, promising to eventually deallocate it
1184 // with free().
1185 // Ex: [NSData dataWithBytesNoCopy:bytes length:10];
1186 // (...unless a 'freeWhenDone' parameter is false, but that's checked later.)
1187 StringRef FirstSlot = Call.getSelector().getNameForSlot(0);
1188 return FirstSlot == "dataWithBytesNoCopy" ||
1189 FirstSlot == "initWithBytesNoCopy" ||
1190 FirstSlot == "initWithCharactersNoCopy";
1191 }
1192
getFreeWhenDoneArg(const ObjCMethodCall & Call)1193 static Optional<bool> getFreeWhenDoneArg(const ObjCMethodCall &Call) {
1194 Selector S = Call.getSelector();
1195
1196 // FIXME: We should not rely on fully-constrained symbols being folded.
1197 for (unsigned i = 1; i < S.getNumArgs(); ++i)
1198 if (S.getNameForSlot(i).equals("freeWhenDone"))
1199 return !Call.getArgSVal(i).isZeroConstant();
1200
1201 return None;
1202 }
1203
checkPostObjCMessage(const ObjCMethodCall & Call,CheckerContext & C) const1204 void MallocChecker::checkPostObjCMessage(const ObjCMethodCall &Call,
1205 CheckerContext &C) const {
1206 if (C.wasInlined)
1207 return;
1208
1209 if (!isKnownDeallocObjCMethodName(Call))
1210 return;
1211
1212 if (Optional<bool> FreeWhenDone = getFreeWhenDoneArg(Call))
1213 if (!*FreeWhenDone)
1214 return;
1215
1216 bool ReleasedAllocatedMemory;
1217 ProgramStateRef State = FreeMemAux(C, Call.getArgExpr(0),
1218 Call.getOriginExpr(), C.getState(),
1219 /*Hold=*/true, ReleasedAllocatedMemory,
1220 /*ReturnsNullOnFailure=*/true);
1221
1222 C.addTransition(State);
1223 }
1224
1225 ProgramStateRef
MallocMemReturnsAttr(CheckerContext & C,const CallExpr * CE,const OwnershipAttr * Att,ProgramStateRef State) const1226 MallocChecker::MallocMemReturnsAttr(CheckerContext &C, const CallExpr *CE,
1227 const OwnershipAttr *Att,
1228 ProgramStateRef State) const {
1229 if (!State)
1230 return nullptr;
1231
1232 if (Att->getModule() != II_malloc)
1233 return nullptr;
1234
1235 OwnershipAttr::args_iterator I = Att->args_begin(), E = Att->args_end();
1236 if (I != E) {
1237 return MallocMemAux(C, CE, CE->getArg(I->getASTIndex()), UndefinedVal(),
1238 State);
1239 }
1240 return MallocMemAux(C, CE, UnknownVal(), UndefinedVal(), State);
1241 }
1242
MallocMemAux(CheckerContext & C,const CallExpr * CE,const Expr * SizeEx,SVal Init,ProgramStateRef State,AllocationFamily Family)1243 ProgramStateRef MallocChecker::MallocMemAux(CheckerContext &C,
1244 const CallExpr *CE,
1245 const Expr *SizeEx, SVal Init,
1246 ProgramStateRef State,
1247 AllocationFamily Family) {
1248 if (!State)
1249 return nullptr;
1250
1251 return MallocMemAux(C, CE, C.getSVal(SizeEx), Init, State, Family);
1252 }
1253
MallocMemAux(CheckerContext & C,const CallExpr * CE,SVal Size,SVal Init,ProgramStateRef State,AllocationFamily Family)1254 ProgramStateRef MallocChecker::MallocMemAux(CheckerContext &C,
1255 const CallExpr *CE,
1256 SVal Size, SVal Init,
1257 ProgramStateRef State,
1258 AllocationFamily Family) {
1259 if (!State)
1260 return nullptr;
1261
1262 // We expect the malloc functions to return a pointer.
1263 if (!Loc::isLocType(CE->getType()))
1264 return nullptr;
1265
1266 // Bind the return value to the symbolic value from the heap region.
1267 // TODO: We could rewrite post visit to eval call; 'malloc' does not have
1268 // side effects other than what we model here.
1269 unsigned Count = C.blockCount();
1270 SValBuilder &svalBuilder = C.getSValBuilder();
1271 const LocationContext *LCtx = C.getPredecessor()->getLocationContext();
1272 DefinedSVal RetVal = svalBuilder.getConjuredHeapSymbolVal(CE, LCtx, Count)
1273 .castAs<DefinedSVal>();
1274 State = State->BindExpr(CE, C.getLocationContext(), RetVal);
1275
1276 // Fill the region with the initialization value.
1277 State = State->bindDefaultInitial(RetVal, Init, LCtx);
1278
1279 // Set the region's extent equal to the Size parameter.
1280 const SymbolicRegion *R =
1281 dyn_cast_or_null<SymbolicRegion>(RetVal.getAsRegion());
1282 if (!R)
1283 return nullptr;
1284 if (Optional<DefinedOrUnknownSVal> DefinedSize =
1285 Size.getAs<DefinedOrUnknownSVal>()) {
1286 SValBuilder &svalBuilder = C.getSValBuilder();
1287 DefinedOrUnknownSVal Extent = R->getExtent(svalBuilder);
1288 DefinedOrUnknownSVal extentMatchesSize =
1289 svalBuilder.evalEQ(State, Extent, *DefinedSize);
1290
1291 State = State->assume(extentMatchesSize, true);
1292 assert(State);
1293 }
1294
1295 return MallocUpdateRefState(C, CE, State, Family);
1296 }
1297
MallocUpdateRefState(CheckerContext & C,const Expr * E,ProgramStateRef State,AllocationFamily Family,Optional<SVal> RetVal)1298 ProgramStateRef MallocChecker::MallocUpdateRefState(CheckerContext &C,
1299 const Expr *E,
1300 ProgramStateRef State,
1301 AllocationFamily Family,
1302 Optional<SVal> RetVal) {
1303 if (!State)
1304 return nullptr;
1305
1306 // Get the return value.
1307 if (!RetVal)
1308 RetVal = C.getSVal(E);
1309
1310 // We expect the malloc functions to return a pointer.
1311 if (!RetVal->getAs<Loc>())
1312 return nullptr;
1313
1314 SymbolRef Sym = RetVal->getAsLocSymbol();
1315 // This is a return value of a function that was not inlined, such as malloc()
1316 // or new(). We've checked that in the caller. Therefore, it must be a symbol.
1317 assert(Sym);
1318
1319 // Set the symbol's state to Allocated.
1320 return State->set<RegionState>(Sym, RefState::getAllocated(Family, E));
1321 }
1322
FreeMemAttr(CheckerContext & C,const CallExpr * CE,const OwnershipAttr * Att,ProgramStateRef State) const1323 ProgramStateRef MallocChecker::FreeMemAttr(CheckerContext &C,
1324 const CallExpr *CE,
1325 const OwnershipAttr *Att,
1326 ProgramStateRef State) const {
1327 if (!State)
1328 return nullptr;
1329
1330 if (Att->getModule() != II_malloc)
1331 return nullptr;
1332
1333 bool ReleasedAllocated = false;
1334
1335 for (const auto &Arg : Att->args()) {
1336 ProgramStateRef StateI = FreeMemAux(
1337 C, CE, State, Arg.getASTIndex(),
1338 Att->getOwnKind() == OwnershipAttr::Holds, ReleasedAllocated);
1339 if (StateI)
1340 State = StateI;
1341 }
1342 return State;
1343 }
1344
FreeMemAux(CheckerContext & C,const CallExpr * CE,ProgramStateRef State,unsigned Num,bool Hold,bool & ReleasedAllocated,bool ReturnsNullOnFailure) const1345 ProgramStateRef MallocChecker::FreeMemAux(CheckerContext &C,
1346 const CallExpr *CE,
1347 ProgramStateRef State,
1348 unsigned Num,
1349 bool Hold,
1350 bool &ReleasedAllocated,
1351 bool ReturnsNullOnFailure) const {
1352 if (!State)
1353 return nullptr;
1354
1355 if (CE->getNumArgs() < (Num + 1))
1356 return nullptr;
1357
1358 return FreeMemAux(C, CE->getArg(Num), CE, State, Hold,
1359 ReleasedAllocated, ReturnsNullOnFailure);
1360 }
1361
1362 /// Checks if the previous call to free on the given symbol failed - if free
1363 /// failed, returns true. Also, returns the corresponding return value symbol.
didPreviousFreeFail(ProgramStateRef State,SymbolRef Sym,SymbolRef & RetStatusSymbol)1364 static bool didPreviousFreeFail(ProgramStateRef State,
1365 SymbolRef Sym, SymbolRef &RetStatusSymbol) {
1366 const SymbolRef *Ret = State->get<FreeReturnValue>(Sym);
1367 if (Ret) {
1368 assert(*Ret && "We should not store the null return symbol");
1369 ConstraintManager &CMgr = State->getConstraintManager();
1370 ConditionTruthVal FreeFailed = CMgr.isNull(State, *Ret);
1371 RetStatusSymbol = *Ret;
1372 return FreeFailed.isConstrainedTrue();
1373 }
1374 return false;
1375 }
1376
getAllocationFamily(CheckerContext & C,const Stmt * S) const1377 AllocationFamily MallocChecker::getAllocationFamily(CheckerContext &C,
1378 const Stmt *S) const {
1379 if (!S)
1380 return AF_None;
1381
1382 if (const CallExpr *CE = dyn_cast<CallExpr>(S)) {
1383 const FunctionDecl *FD = C.getCalleeDecl(CE);
1384
1385 if (!FD)
1386 FD = dyn_cast<FunctionDecl>(CE->getCalleeDecl());
1387
1388 ASTContext &Ctx = C.getASTContext();
1389
1390 if (isCMemFunction(FD, Ctx, AF_Malloc, MemoryOperationKind::MOK_Any))
1391 return AF_Malloc;
1392
1393 if (isStandardNewDelete(FD, Ctx)) {
1394 OverloadedOperatorKind Kind = FD->getOverloadedOperator();
1395 if (Kind == OO_New || Kind == OO_Delete)
1396 return AF_CXXNew;
1397 else if (Kind == OO_Array_New || Kind == OO_Array_Delete)
1398 return AF_CXXNewArray;
1399 }
1400
1401 if (isCMemFunction(FD, Ctx, AF_IfNameIndex, MemoryOperationKind::MOK_Any))
1402 return AF_IfNameIndex;
1403
1404 if (isCMemFunction(FD, Ctx, AF_Alloca, MemoryOperationKind::MOK_Any))
1405 return AF_Alloca;
1406
1407 return AF_None;
1408 }
1409
1410 if (const CXXNewExpr *NE = dyn_cast<CXXNewExpr>(S))
1411 return NE->isArray() ? AF_CXXNewArray : AF_CXXNew;
1412
1413 if (const CXXDeleteExpr *DE = dyn_cast<CXXDeleteExpr>(S))
1414 return DE->isArrayForm() ? AF_CXXNewArray : AF_CXXNew;
1415
1416 if (isa<ObjCMessageExpr>(S))
1417 return AF_Malloc;
1418
1419 return AF_None;
1420 }
1421
printAllocDeallocName(raw_ostream & os,CheckerContext & C,const Expr * E) const1422 bool MallocChecker::printAllocDeallocName(raw_ostream &os, CheckerContext &C,
1423 const Expr *E) const {
1424 if (const CallExpr *CE = dyn_cast<CallExpr>(E)) {
1425 // FIXME: This doesn't handle indirect calls.
1426 const FunctionDecl *FD = CE->getDirectCallee();
1427 if (!FD)
1428 return false;
1429
1430 os << *FD;
1431 if (!FD->isOverloadedOperator())
1432 os << "()";
1433 return true;
1434 }
1435
1436 if (const ObjCMessageExpr *Msg = dyn_cast<ObjCMessageExpr>(E)) {
1437 if (Msg->isInstanceMessage())
1438 os << "-";
1439 else
1440 os << "+";
1441 Msg->getSelector().print(os);
1442 return true;
1443 }
1444
1445 if (const CXXNewExpr *NE = dyn_cast<CXXNewExpr>(E)) {
1446 os << "'"
1447 << getOperatorSpelling(NE->getOperatorNew()->getOverloadedOperator())
1448 << "'";
1449 return true;
1450 }
1451
1452 if (const CXXDeleteExpr *DE = dyn_cast<CXXDeleteExpr>(E)) {
1453 os << "'"
1454 << getOperatorSpelling(DE->getOperatorDelete()->getOverloadedOperator())
1455 << "'";
1456 return true;
1457 }
1458
1459 return false;
1460 }
1461
printExpectedAllocName(raw_ostream & os,CheckerContext & C,const Expr * E) const1462 void MallocChecker::printExpectedAllocName(raw_ostream &os, CheckerContext &C,
1463 const Expr *E) const {
1464 AllocationFamily Family = getAllocationFamily(C, E);
1465
1466 switch(Family) {
1467 case AF_Malloc: os << "malloc()"; return;
1468 case AF_CXXNew: os << "'new'"; return;
1469 case AF_CXXNewArray: os << "'new[]'"; return;
1470 case AF_IfNameIndex: os << "'if_nameindex()'"; return;
1471 case AF_InnerBuffer: os << "container-specific allocator"; return;
1472 case AF_Alloca:
1473 case AF_None: llvm_unreachable("not a deallocation expression");
1474 }
1475 }
1476
printExpectedDeallocName(raw_ostream & os,AllocationFamily Family) const1477 void MallocChecker::printExpectedDeallocName(raw_ostream &os,
1478 AllocationFamily Family) const {
1479 switch(Family) {
1480 case AF_Malloc: os << "free()"; return;
1481 case AF_CXXNew: os << "'delete'"; return;
1482 case AF_CXXNewArray: os << "'delete[]'"; return;
1483 case AF_IfNameIndex: os << "'if_freenameindex()'"; return;
1484 case AF_InnerBuffer: os << "container-specific deallocator"; return;
1485 case AF_Alloca:
1486 case AF_None: llvm_unreachable("suspicious argument");
1487 }
1488 }
1489
FreeMemAux(CheckerContext & C,const Expr * ArgExpr,const Expr * ParentExpr,ProgramStateRef State,bool Hold,bool & ReleasedAllocated,bool ReturnsNullOnFailure) const1490 ProgramStateRef MallocChecker::FreeMemAux(CheckerContext &C,
1491 const Expr *ArgExpr,
1492 const Expr *ParentExpr,
1493 ProgramStateRef State,
1494 bool Hold,
1495 bool &ReleasedAllocated,
1496 bool ReturnsNullOnFailure) const {
1497
1498 if (!State)
1499 return nullptr;
1500
1501 SVal ArgVal = C.getSVal(ArgExpr);
1502 if (!ArgVal.getAs<DefinedOrUnknownSVal>())
1503 return nullptr;
1504 DefinedOrUnknownSVal location = ArgVal.castAs<DefinedOrUnknownSVal>();
1505
1506 // Check for null dereferences.
1507 if (!location.getAs<Loc>())
1508 return nullptr;
1509
1510 // The explicit NULL case, no operation is performed.
1511 ProgramStateRef notNullState, nullState;
1512 std::tie(notNullState, nullState) = State->assume(location);
1513 if (nullState && !notNullState)
1514 return nullptr;
1515
1516 // Unknown values could easily be okay
1517 // Undefined values are handled elsewhere
1518 if (ArgVal.isUnknownOrUndef())
1519 return nullptr;
1520
1521 const MemRegion *R = ArgVal.getAsRegion();
1522
1523 // Nonlocs can't be freed, of course.
1524 // Non-region locations (labels and fixed addresses) also shouldn't be freed.
1525 if (!R) {
1526 ReportBadFree(C, ArgVal, ArgExpr->getSourceRange(), ParentExpr);
1527 return nullptr;
1528 }
1529
1530 R = R->StripCasts();
1531
1532 // Blocks might show up as heap data, but should not be free()d
1533 if (isa<BlockDataRegion>(R)) {
1534 ReportBadFree(C, ArgVal, ArgExpr->getSourceRange(), ParentExpr);
1535 return nullptr;
1536 }
1537
1538 const MemSpaceRegion *MS = R->getMemorySpace();
1539
1540 // Parameters, locals, statics, globals, and memory returned by
1541 // __builtin_alloca() shouldn't be freed.
1542 if (!(isa<UnknownSpaceRegion>(MS) || isa<HeapSpaceRegion>(MS))) {
1543 // FIXME: at the time this code was written, malloc() regions were
1544 // represented by conjured symbols, which are all in UnknownSpaceRegion.
1545 // This means that there isn't actually anything from HeapSpaceRegion
1546 // that should be freed, even though we allow it here.
1547 // Of course, free() can work on memory allocated outside the current
1548 // function, so UnknownSpaceRegion is always a possibility.
1549 // False negatives are better than false positives.
1550
1551 if (isa<AllocaRegion>(R))
1552 ReportFreeAlloca(C, ArgVal, ArgExpr->getSourceRange());
1553 else
1554 ReportBadFree(C, ArgVal, ArgExpr->getSourceRange(), ParentExpr);
1555
1556 return nullptr;
1557 }
1558
1559 const SymbolicRegion *SrBase = dyn_cast<SymbolicRegion>(R->getBaseRegion());
1560 // Various cases could lead to non-symbol values here.
1561 // For now, ignore them.
1562 if (!SrBase)
1563 return nullptr;
1564
1565 SymbolRef SymBase = SrBase->getSymbol();
1566 const RefState *RsBase = State->get<RegionState>(SymBase);
1567 SymbolRef PreviousRetStatusSymbol = nullptr;
1568
1569 if (RsBase) {
1570
1571 // Memory returned by alloca() shouldn't be freed.
1572 if (RsBase->getAllocationFamily() == AF_Alloca) {
1573 ReportFreeAlloca(C, ArgVal, ArgExpr->getSourceRange());
1574 return nullptr;
1575 }
1576
1577 // Check for double free first.
1578 if ((RsBase->isReleased() || RsBase->isRelinquished()) &&
1579 !didPreviousFreeFail(State, SymBase, PreviousRetStatusSymbol)) {
1580 ReportDoubleFree(C, ParentExpr->getSourceRange(), RsBase->isReleased(),
1581 SymBase, PreviousRetStatusSymbol);
1582 return nullptr;
1583
1584 // If the pointer is allocated or escaped, but we are now trying to free it,
1585 // check that the call to free is proper.
1586 } else if (RsBase->isAllocated() || RsBase->isAllocatedOfSizeZero() ||
1587 RsBase->isEscaped()) {
1588
1589 // Check if an expected deallocation function matches the real one.
1590 bool DeallocMatchesAlloc =
1591 RsBase->getAllocationFamily() == getAllocationFamily(C, ParentExpr);
1592 if (!DeallocMatchesAlloc) {
1593 ReportMismatchedDealloc(C, ArgExpr->getSourceRange(),
1594 ParentExpr, RsBase, SymBase, Hold);
1595 return nullptr;
1596 }
1597
1598 // Check if the memory location being freed is the actual location
1599 // allocated, or an offset.
1600 RegionOffset Offset = R->getAsOffset();
1601 if (Offset.isValid() &&
1602 !Offset.hasSymbolicOffset() &&
1603 Offset.getOffset() != 0) {
1604 const Expr *AllocExpr = cast<Expr>(RsBase->getStmt());
1605 ReportOffsetFree(C, ArgVal, ArgExpr->getSourceRange(), ParentExpr,
1606 AllocExpr);
1607 return nullptr;
1608 }
1609 }
1610 }
1611
1612 if (SymBase->getType()->isFunctionPointerType()) {
1613 ReportFunctionPointerFree(C, ArgVal, ArgExpr->getSourceRange(), ParentExpr);
1614 return nullptr;
1615 }
1616
1617 ReleasedAllocated = (RsBase != nullptr) && (RsBase->isAllocated() ||
1618 RsBase->isAllocatedOfSizeZero());
1619
1620 // Clean out the info on previous call to free return info.
1621 State = State->remove<FreeReturnValue>(SymBase);
1622
1623 // Keep track of the return value. If it is NULL, we will know that free
1624 // failed.
1625 if (ReturnsNullOnFailure) {
1626 SVal RetVal = C.getSVal(ParentExpr);
1627 SymbolRef RetStatusSymbol = RetVal.getAsSymbol();
1628 if (RetStatusSymbol) {
1629 C.getSymbolManager().addSymbolDependency(SymBase, RetStatusSymbol);
1630 State = State->set<FreeReturnValue>(SymBase, RetStatusSymbol);
1631 }
1632 }
1633
1634 AllocationFamily Family = RsBase ? RsBase->getAllocationFamily()
1635 : getAllocationFamily(C, ParentExpr);
1636 // Normal free.
1637 if (Hold)
1638 return State->set<RegionState>(SymBase,
1639 RefState::getRelinquished(Family,
1640 ParentExpr));
1641
1642 return State->set<RegionState>(SymBase,
1643 RefState::getReleased(Family, ParentExpr));
1644 }
1645
1646 Optional<MallocChecker::CheckKind>
getCheckIfTracked(AllocationFamily Family,bool IsALeakCheck) const1647 MallocChecker::getCheckIfTracked(AllocationFamily Family,
1648 bool IsALeakCheck) const {
1649 switch (Family) {
1650 case AF_Malloc:
1651 case AF_Alloca:
1652 case AF_IfNameIndex: {
1653 if (ChecksEnabled[CK_MallocChecker])
1654 return CK_MallocChecker;
1655 return None;
1656 }
1657 case AF_CXXNew:
1658 case AF_CXXNewArray: {
1659 if (IsALeakCheck) {
1660 if (ChecksEnabled[CK_NewDeleteLeaksChecker])
1661 return CK_NewDeleteLeaksChecker;
1662 }
1663 else {
1664 if (ChecksEnabled[CK_NewDeleteChecker])
1665 return CK_NewDeleteChecker;
1666 }
1667 return None;
1668 }
1669 case AF_InnerBuffer: {
1670 if (ChecksEnabled[CK_InnerPointerChecker])
1671 return CK_InnerPointerChecker;
1672 return None;
1673 }
1674 case AF_None: {
1675 llvm_unreachable("no family");
1676 }
1677 }
1678 llvm_unreachable("unhandled family");
1679 }
1680
1681 Optional<MallocChecker::CheckKind>
getCheckIfTracked(CheckerContext & C,const Stmt * AllocDeallocStmt,bool IsALeakCheck) const1682 MallocChecker::getCheckIfTracked(CheckerContext &C,
1683 const Stmt *AllocDeallocStmt,
1684 bool IsALeakCheck) const {
1685 return getCheckIfTracked(getAllocationFamily(C, AllocDeallocStmt),
1686 IsALeakCheck);
1687 }
1688
1689 Optional<MallocChecker::CheckKind>
getCheckIfTracked(CheckerContext & C,SymbolRef Sym,bool IsALeakCheck) const1690 MallocChecker::getCheckIfTracked(CheckerContext &C, SymbolRef Sym,
1691 bool IsALeakCheck) const {
1692 if (C.getState()->contains<ReallocSizeZeroSymbols>(Sym))
1693 return CK_MallocChecker;
1694
1695 const RefState *RS = C.getState()->get<RegionState>(Sym);
1696 assert(RS);
1697 return getCheckIfTracked(RS->getAllocationFamily(), IsALeakCheck);
1698 }
1699
SummarizeValue(raw_ostream & os,SVal V)1700 bool MallocChecker::SummarizeValue(raw_ostream &os, SVal V) {
1701 if (Optional<nonloc::ConcreteInt> IntVal = V.getAs<nonloc::ConcreteInt>())
1702 os << "an integer (" << IntVal->getValue() << ")";
1703 else if (Optional<loc::ConcreteInt> ConstAddr = V.getAs<loc::ConcreteInt>())
1704 os << "a constant address (" << ConstAddr->getValue() << ")";
1705 else if (Optional<loc::GotoLabel> Label = V.getAs<loc::GotoLabel>())
1706 os << "the address of the label '" << Label->getLabel()->getName() << "'";
1707 else
1708 return false;
1709
1710 return true;
1711 }
1712
SummarizeRegion(raw_ostream & os,const MemRegion * MR)1713 bool MallocChecker::SummarizeRegion(raw_ostream &os,
1714 const MemRegion *MR) {
1715 switch (MR->getKind()) {
1716 case MemRegion::FunctionCodeRegionKind: {
1717 const NamedDecl *FD = cast<FunctionCodeRegion>(MR)->getDecl();
1718 if (FD)
1719 os << "the address of the function '" << *FD << '\'';
1720 else
1721 os << "the address of a function";
1722 return true;
1723 }
1724 case MemRegion::BlockCodeRegionKind:
1725 os << "block text";
1726 return true;
1727 case MemRegion::BlockDataRegionKind:
1728 // FIXME: where the block came from?
1729 os << "a block";
1730 return true;
1731 default: {
1732 const MemSpaceRegion *MS = MR->getMemorySpace();
1733
1734 if (isa<StackLocalsSpaceRegion>(MS)) {
1735 const VarRegion *VR = dyn_cast<VarRegion>(MR);
1736 const VarDecl *VD;
1737 if (VR)
1738 VD = VR->getDecl();
1739 else
1740 VD = nullptr;
1741
1742 if (VD)
1743 os << "the address of the local variable '" << VD->getName() << "'";
1744 else
1745 os << "the address of a local stack variable";
1746 return true;
1747 }
1748
1749 if (isa<StackArgumentsSpaceRegion>(MS)) {
1750 const VarRegion *VR = dyn_cast<VarRegion>(MR);
1751 const VarDecl *VD;
1752 if (VR)
1753 VD = VR->getDecl();
1754 else
1755 VD = nullptr;
1756
1757 if (VD)
1758 os << "the address of the parameter '" << VD->getName() << "'";
1759 else
1760 os << "the address of a parameter";
1761 return true;
1762 }
1763
1764 if (isa<GlobalsSpaceRegion>(MS)) {
1765 const VarRegion *VR = dyn_cast<VarRegion>(MR);
1766 const VarDecl *VD;
1767 if (VR)
1768 VD = VR->getDecl();
1769 else
1770 VD = nullptr;
1771
1772 if (VD) {
1773 if (VD->isStaticLocal())
1774 os << "the address of the static variable '" << VD->getName() << "'";
1775 else
1776 os << "the address of the global variable '" << VD->getName() << "'";
1777 } else
1778 os << "the address of a global variable";
1779 return true;
1780 }
1781
1782 return false;
1783 }
1784 }
1785 }
1786
ReportBadFree(CheckerContext & C,SVal ArgVal,SourceRange Range,const Expr * DeallocExpr) const1787 void MallocChecker::ReportBadFree(CheckerContext &C, SVal ArgVal,
1788 SourceRange Range,
1789 const Expr *DeallocExpr) const {
1790
1791 if (!ChecksEnabled[CK_MallocChecker] &&
1792 !ChecksEnabled[CK_NewDeleteChecker])
1793 return;
1794
1795 Optional<MallocChecker::CheckKind> CheckKind =
1796 getCheckIfTracked(C, DeallocExpr);
1797 if (!CheckKind.hasValue())
1798 return;
1799
1800 if (ExplodedNode *N = C.generateErrorNode()) {
1801 if (!BT_BadFree[*CheckKind])
1802 BT_BadFree[*CheckKind].reset(new BugType(
1803 CheckNames[*CheckKind], "Bad free", categories::MemoryError));
1804
1805 SmallString<100> buf;
1806 llvm::raw_svector_ostream os(buf);
1807
1808 const MemRegion *MR = ArgVal.getAsRegion();
1809 while (const ElementRegion *ER = dyn_cast_or_null<ElementRegion>(MR))
1810 MR = ER->getSuperRegion();
1811
1812 os << "Argument to ";
1813 if (!printAllocDeallocName(os, C, DeallocExpr))
1814 os << "deallocator";
1815
1816 os << " is ";
1817 bool Summarized = MR ? SummarizeRegion(os, MR)
1818 : SummarizeValue(os, ArgVal);
1819 if (Summarized)
1820 os << ", which is not memory allocated by ";
1821 else
1822 os << "not memory allocated by ";
1823
1824 printExpectedAllocName(os, C, DeallocExpr);
1825
1826 auto R = llvm::make_unique<BugReport>(*BT_BadFree[*CheckKind], os.str(), N);
1827 R->markInteresting(MR);
1828 R->addRange(Range);
1829 C.emitReport(std::move(R));
1830 }
1831 }
1832
ReportFreeAlloca(CheckerContext & C,SVal ArgVal,SourceRange Range) const1833 void MallocChecker::ReportFreeAlloca(CheckerContext &C, SVal ArgVal,
1834 SourceRange Range) const {
1835
1836 Optional<MallocChecker::CheckKind> CheckKind;
1837
1838 if (ChecksEnabled[CK_MallocChecker])
1839 CheckKind = CK_MallocChecker;
1840 else if (ChecksEnabled[CK_MismatchedDeallocatorChecker])
1841 CheckKind = CK_MismatchedDeallocatorChecker;
1842 else
1843 return;
1844
1845 if (ExplodedNode *N = C.generateErrorNode()) {
1846 if (!BT_FreeAlloca[*CheckKind])
1847 BT_FreeAlloca[*CheckKind].reset(new BugType(
1848 CheckNames[*CheckKind], "Free alloca()", categories::MemoryError));
1849
1850 auto R = llvm::make_unique<BugReport>(
1851 *BT_FreeAlloca[*CheckKind],
1852 "Memory allocated by alloca() should not be deallocated", N);
1853 R->markInteresting(ArgVal.getAsRegion());
1854 R->addRange(Range);
1855 C.emitReport(std::move(R));
1856 }
1857 }
1858
ReportMismatchedDealloc(CheckerContext & C,SourceRange Range,const Expr * DeallocExpr,const RefState * RS,SymbolRef Sym,bool OwnershipTransferred) const1859 void MallocChecker::ReportMismatchedDealloc(CheckerContext &C,
1860 SourceRange Range,
1861 const Expr *DeallocExpr,
1862 const RefState *RS,
1863 SymbolRef Sym,
1864 bool OwnershipTransferred) const {
1865
1866 if (!ChecksEnabled[CK_MismatchedDeallocatorChecker])
1867 return;
1868
1869 if (ExplodedNode *N = C.generateErrorNode()) {
1870 if (!BT_MismatchedDealloc)
1871 BT_MismatchedDealloc.reset(
1872 new BugType(CheckNames[CK_MismatchedDeallocatorChecker],
1873 "Bad deallocator", categories::MemoryError));
1874
1875 SmallString<100> buf;
1876 llvm::raw_svector_ostream os(buf);
1877
1878 const Expr *AllocExpr = cast<Expr>(RS->getStmt());
1879 SmallString<20> AllocBuf;
1880 llvm::raw_svector_ostream AllocOs(AllocBuf);
1881 SmallString<20> DeallocBuf;
1882 llvm::raw_svector_ostream DeallocOs(DeallocBuf);
1883
1884 if (OwnershipTransferred) {
1885 if (printAllocDeallocName(DeallocOs, C, DeallocExpr))
1886 os << DeallocOs.str() << " cannot";
1887 else
1888 os << "Cannot";
1889
1890 os << " take ownership of memory";
1891
1892 if (printAllocDeallocName(AllocOs, C, AllocExpr))
1893 os << " allocated by " << AllocOs.str();
1894 } else {
1895 os << "Memory";
1896 if (printAllocDeallocName(AllocOs, C, AllocExpr))
1897 os << " allocated by " << AllocOs.str();
1898
1899 os << " should be deallocated by ";
1900 printExpectedDeallocName(os, RS->getAllocationFamily());
1901
1902 if (printAllocDeallocName(DeallocOs, C, DeallocExpr))
1903 os << ", not " << DeallocOs.str();
1904 }
1905
1906 auto R = llvm::make_unique<BugReport>(*BT_MismatchedDealloc, os.str(), N);
1907 R->markInteresting(Sym);
1908 R->addRange(Range);
1909 R->addVisitor(llvm::make_unique<MallocBugVisitor>(Sym));
1910 C.emitReport(std::move(R));
1911 }
1912 }
1913
ReportOffsetFree(CheckerContext & C,SVal ArgVal,SourceRange Range,const Expr * DeallocExpr,const Expr * AllocExpr) const1914 void MallocChecker::ReportOffsetFree(CheckerContext &C, SVal ArgVal,
1915 SourceRange Range, const Expr *DeallocExpr,
1916 const Expr *AllocExpr) const {
1917
1918
1919 if (!ChecksEnabled[CK_MallocChecker] &&
1920 !ChecksEnabled[CK_NewDeleteChecker])
1921 return;
1922
1923 Optional<MallocChecker::CheckKind> CheckKind =
1924 getCheckIfTracked(C, AllocExpr);
1925 if (!CheckKind.hasValue())
1926 return;
1927
1928 ExplodedNode *N = C.generateErrorNode();
1929 if (!N)
1930 return;
1931
1932 if (!BT_OffsetFree[*CheckKind])
1933 BT_OffsetFree[*CheckKind].reset(new BugType(
1934 CheckNames[*CheckKind], "Offset free", categories::MemoryError));
1935
1936 SmallString<100> buf;
1937 llvm::raw_svector_ostream os(buf);
1938 SmallString<20> AllocNameBuf;
1939 llvm::raw_svector_ostream AllocNameOs(AllocNameBuf);
1940
1941 const MemRegion *MR = ArgVal.getAsRegion();
1942 assert(MR && "Only MemRegion based symbols can have offset free errors");
1943
1944 RegionOffset Offset = MR->getAsOffset();
1945 assert((Offset.isValid() &&
1946 !Offset.hasSymbolicOffset() &&
1947 Offset.getOffset() != 0) &&
1948 "Only symbols with a valid offset can have offset free errors");
1949
1950 int offsetBytes = Offset.getOffset() / C.getASTContext().getCharWidth();
1951
1952 os << "Argument to ";
1953 if (!printAllocDeallocName(os, C, DeallocExpr))
1954 os << "deallocator";
1955 os << " is offset by "
1956 << offsetBytes
1957 << " "
1958 << ((abs(offsetBytes) > 1) ? "bytes" : "byte")
1959 << " from the start of ";
1960 if (AllocExpr && printAllocDeallocName(AllocNameOs, C, AllocExpr))
1961 os << "memory allocated by " << AllocNameOs.str();
1962 else
1963 os << "allocated memory";
1964
1965 auto R = llvm::make_unique<BugReport>(*BT_OffsetFree[*CheckKind], os.str(), N);
1966 R->markInteresting(MR->getBaseRegion());
1967 R->addRange(Range);
1968 C.emitReport(std::move(R));
1969 }
1970
ReportUseAfterFree(CheckerContext & C,SourceRange Range,SymbolRef Sym) const1971 void MallocChecker::ReportUseAfterFree(CheckerContext &C, SourceRange Range,
1972 SymbolRef Sym) const {
1973
1974 if (!ChecksEnabled[CK_MallocChecker] &&
1975 !ChecksEnabled[CK_NewDeleteChecker] &&
1976 !ChecksEnabled[CK_InnerPointerChecker])
1977 return;
1978
1979 Optional<MallocChecker::CheckKind> CheckKind = getCheckIfTracked(C, Sym);
1980 if (!CheckKind.hasValue())
1981 return;
1982
1983 if (ExplodedNode *N = C.generateErrorNode()) {
1984 if (!BT_UseFree[*CheckKind])
1985 BT_UseFree[*CheckKind].reset(new BugType(
1986 CheckNames[*CheckKind], "Use-after-free", categories::MemoryError));
1987
1988 AllocationFamily AF =
1989 C.getState()->get<RegionState>(Sym)->getAllocationFamily();
1990
1991 auto R = llvm::make_unique<BugReport>(*BT_UseFree[*CheckKind],
1992 AF == AF_InnerBuffer
1993 ? "Inner pointer of container used after re/deallocation"
1994 : "Use of memory after it is freed",
1995 N);
1996
1997 R->markInteresting(Sym);
1998 R->addRange(Range);
1999 R->addVisitor(llvm::make_unique<MallocBugVisitor>(Sym));
2000
2001 if (AF == AF_InnerBuffer)
2002 R->addVisitor(allocation_state::getInnerPointerBRVisitor(Sym));
2003
2004 C.emitReport(std::move(R));
2005 }
2006 }
2007
ReportDoubleFree(CheckerContext & C,SourceRange Range,bool Released,SymbolRef Sym,SymbolRef PrevSym) const2008 void MallocChecker::ReportDoubleFree(CheckerContext &C, SourceRange Range,
2009 bool Released, SymbolRef Sym,
2010 SymbolRef PrevSym) const {
2011
2012 if (!ChecksEnabled[CK_MallocChecker] &&
2013 !ChecksEnabled[CK_NewDeleteChecker])
2014 return;
2015
2016 Optional<MallocChecker::CheckKind> CheckKind = getCheckIfTracked(C, Sym);
2017 if (!CheckKind.hasValue())
2018 return;
2019
2020 if (ExplodedNode *N = C.generateErrorNode()) {
2021 if (!BT_DoubleFree[*CheckKind])
2022 BT_DoubleFree[*CheckKind].reset(new BugType(
2023 CheckNames[*CheckKind], "Double free", categories::MemoryError));
2024
2025 auto R = llvm::make_unique<BugReport>(
2026 *BT_DoubleFree[*CheckKind],
2027 (Released ? "Attempt to free released memory"
2028 : "Attempt to free non-owned memory"),
2029 N);
2030 R->addRange(Range);
2031 R->markInteresting(Sym);
2032 if (PrevSym)
2033 R->markInteresting(PrevSym);
2034 R->addVisitor(llvm::make_unique<MallocBugVisitor>(Sym));
2035 C.emitReport(std::move(R));
2036 }
2037 }
2038
ReportDoubleDelete(CheckerContext & C,SymbolRef Sym) const2039 void MallocChecker::ReportDoubleDelete(CheckerContext &C, SymbolRef Sym) const {
2040
2041 if (!ChecksEnabled[CK_NewDeleteChecker])
2042 return;
2043
2044 Optional<MallocChecker::CheckKind> CheckKind = getCheckIfTracked(C, Sym);
2045 if (!CheckKind.hasValue())
2046 return;
2047
2048 if (ExplodedNode *N = C.generateErrorNode()) {
2049 if (!BT_DoubleDelete)
2050 BT_DoubleDelete.reset(new BugType(CheckNames[CK_NewDeleteChecker],
2051 "Double delete",
2052 categories::MemoryError));
2053
2054 auto R = llvm::make_unique<BugReport>(
2055 *BT_DoubleDelete, "Attempt to delete released memory", N);
2056
2057 R->markInteresting(Sym);
2058 R->addVisitor(llvm::make_unique<MallocBugVisitor>(Sym));
2059 C.emitReport(std::move(R));
2060 }
2061 }
2062
ReportUseZeroAllocated(CheckerContext & C,SourceRange Range,SymbolRef Sym) const2063 void MallocChecker::ReportUseZeroAllocated(CheckerContext &C,
2064 SourceRange Range,
2065 SymbolRef Sym) const {
2066
2067 if (!ChecksEnabled[CK_MallocChecker] &&
2068 !ChecksEnabled[CK_NewDeleteChecker])
2069 return;
2070
2071 Optional<MallocChecker::CheckKind> CheckKind = getCheckIfTracked(C, Sym);
2072
2073 if (!CheckKind.hasValue())
2074 return;
2075
2076 if (ExplodedNode *N = C.generateErrorNode()) {
2077 if (!BT_UseZerroAllocated[*CheckKind])
2078 BT_UseZerroAllocated[*CheckKind].reset(
2079 new BugType(CheckNames[*CheckKind], "Use of zero allocated",
2080 categories::MemoryError));
2081
2082 auto R = llvm::make_unique<BugReport>(*BT_UseZerroAllocated[*CheckKind],
2083 "Use of zero-allocated memory", N);
2084
2085 R->addRange(Range);
2086 if (Sym) {
2087 R->markInteresting(Sym);
2088 R->addVisitor(llvm::make_unique<MallocBugVisitor>(Sym));
2089 }
2090 C.emitReport(std::move(R));
2091 }
2092 }
2093
ReportFunctionPointerFree(CheckerContext & C,SVal ArgVal,SourceRange Range,const Expr * FreeExpr) const2094 void MallocChecker::ReportFunctionPointerFree(CheckerContext &C, SVal ArgVal,
2095 SourceRange Range,
2096 const Expr *FreeExpr) const {
2097 if (!ChecksEnabled[CK_MallocChecker])
2098 return;
2099
2100 Optional<MallocChecker::CheckKind> CheckKind = getCheckIfTracked(C, FreeExpr);
2101 if (!CheckKind.hasValue())
2102 return;
2103
2104 if (ExplodedNode *N = C.generateErrorNode()) {
2105 if (!BT_BadFree[*CheckKind])
2106 BT_BadFree[*CheckKind].reset(new BugType(
2107 CheckNames[*CheckKind], "Bad free", categories::MemoryError));
2108
2109 SmallString<100> Buf;
2110 llvm::raw_svector_ostream Os(Buf);
2111
2112 const MemRegion *MR = ArgVal.getAsRegion();
2113 while (const ElementRegion *ER = dyn_cast_or_null<ElementRegion>(MR))
2114 MR = ER->getSuperRegion();
2115
2116 Os << "Argument to ";
2117 if (!printAllocDeallocName(Os, C, FreeExpr))
2118 Os << "deallocator";
2119
2120 Os << " is a function pointer";
2121
2122 auto R = llvm::make_unique<BugReport>(*BT_BadFree[*CheckKind], Os.str(), N);
2123 R->markInteresting(MR);
2124 R->addRange(Range);
2125 C.emitReport(std::move(R));
2126 }
2127 }
2128
ReallocMemAux(CheckerContext & C,const CallExpr * CE,bool FreesOnFail,ProgramStateRef State,bool SuffixWithN) const2129 ProgramStateRef MallocChecker::ReallocMemAux(CheckerContext &C,
2130 const CallExpr *CE,
2131 bool FreesOnFail,
2132 ProgramStateRef State,
2133 bool SuffixWithN) const {
2134 if (!State)
2135 return nullptr;
2136
2137 if (SuffixWithN && CE->getNumArgs() < 3)
2138 return nullptr;
2139 else if (CE->getNumArgs() < 2)
2140 return nullptr;
2141
2142 const Expr *arg0Expr = CE->getArg(0);
2143 SVal Arg0Val = C.getSVal(arg0Expr);
2144 if (!Arg0Val.getAs<DefinedOrUnknownSVal>())
2145 return nullptr;
2146 DefinedOrUnknownSVal arg0Val = Arg0Val.castAs<DefinedOrUnknownSVal>();
2147
2148 SValBuilder &svalBuilder = C.getSValBuilder();
2149
2150 DefinedOrUnknownSVal PtrEQ =
2151 svalBuilder.evalEQ(State, arg0Val, svalBuilder.makeNull());
2152
2153 // Get the size argument.
2154 const Expr *Arg1 = CE->getArg(1);
2155
2156 // Get the value of the size argument.
2157 SVal TotalSize = C.getSVal(Arg1);
2158 if (SuffixWithN)
2159 TotalSize = evalMulForBufferSize(C, Arg1, CE->getArg(2));
2160 if (!TotalSize.getAs<DefinedOrUnknownSVal>())
2161 return nullptr;
2162
2163 // Compare the size argument to 0.
2164 DefinedOrUnknownSVal SizeZero =
2165 svalBuilder.evalEQ(State, TotalSize.castAs<DefinedOrUnknownSVal>(),
2166 svalBuilder.makeIntValWithPtrWidth(0, false));
2167
2168 ProgramStateRef StatePtrIsNull, StatePtrNotNull;
2169 std::tie(StatePtrIsNull, StatePtrNotNull) = State->assume(PtrEQ);
2170 ProgramStateRef StateSizeIsZero, StateSizeNotZero;
2171 std::tie(StateSizeIsZero, StateSizeNotZero) = State->assume(SizeZero);
2172 // We only assume exceptional states if they are definitely true; if the
2173 // state is under-constrained, assume regular realloc behavior.
2174 bool PrtIsNull = StatePtrIsNull && !StatePtrNotNull;
2175 bool SizeIsZero = StateSizeIsZero && !StateSizeNotZero;
2176
2177 // If the ptr is NULL and the size is not 0, the call is equivalent to
2178 // malloc(size).
2179 if (PrtIsNull && !SizeIsZero) {
2180 ProgramStateRef stateMalloc = MallocMemAux(C, CE, TotalSize,
2181 UndefinedVal(), StatePtrIsNull);
2182 return stateMalloc;
2183 }
2184
2185 if (PrtIsNull && SizeIsZero)
2186 return State;
2187
2188 // Get the from and to pointer symbols as in toPtr = realloc(fromPtr, size).
2189 assert(!PrtIsNull);
2190 SymbolRef FromPtr = arg0Val.getAsSymbol();
2191 SVal RetVal = C.getSVal(CE);
2192 SymbolRef ToPtr = RetVal.getAsSymbol();
2193 if (!FromPtr || !ToPtr)
2194 return nullptr;
2195
2196 bool ReleasedAllocated = false;
2197
2198 // If the size is 0, free the memory.
2199 if (SizeIsZero)
2200 if (ProgramStateRef stateFree = FreeMemAux(C, CE, StateSizeIsZero, 0,
2201 false, ReleasedAllocated)){
2202 // The semantics of the return value are:
2203 // If size was equal to 0, either NULL or a pointer suitable to be passed
2204 // to free() is returned. We just free the input pointer and do not add
2205 // any constrains on the output pointer.
2206 return stateFree;
2207 }
2208
2209 // Default behavior.
2210 if (ProgramStateRef stateFree =
2211 FreeMemAux(C, CE, State, 0, false, ReleasedAllocated)) {
2212
2213 ProgramStateRef stateRealloc = MallocMemAux(C, CE, TotalSize,
2214 UnknownVal(), stateFree);
2215 if (!stateRealloc)
2216 return nullptr;
2217
2218 ReallocPairKind Kind = RPToBeFreedAfterFailure;
2219 if (FreesOnFail)
2220 Kind = RPIsFreeOnFailure;
2221 else if (!ReleasedAllocated)
2222 Kind = RPDoNotTrackAfterFailure;
2223
2224 // Record the info about the reallocated symbol so that we could properly
2225 // process failed reallocation.
2226 stateRealloc = stateRealloc->set<ReallocPairs>(ToPtr,
2227 ReallocPair(FromPtr, Kind));
2228 // The reallocated symbol should stay alive for as long as the new symbol.
2229 C.getSymbolManager().addSymbolDependency(ToPtr, FromPtr);
2230 return stateRealloc;
2231 }
2232 return nullptr;
2233 }
2234
CallocMem(CheckerContext & C,const CallExpr * CE,ProgramStateRef State)2235 ProgramStateRef MallocChecker::CallocMem(CheckerContext &C, const CallExpr *CE,
2236 ProgramStateRef State) {
2237 if (!State)
2238 return nullptr;
2239
2240 if (CE->getNumArgs() < 2)
2241 return nullptr;
2242
2243 SValBuilder &svalBuilder = C.getSValBuilder();
2244 SVal zeroVal = svalBuilder.makeZeroVal(svalBuilder.getContext().CharTy);
2245 SVal TotalSize = evalMulForBufferSize(C, CE->getArg(0), CE->getArg(1));
2246
2247 return MallocMemAux(C, CE, TotalSize, zeroVal, State);
2248 }
2249
2250 LeakInfo
getAllocationSite(const ExplodedNode * N,SymbolRef Sym,CheckerContext & C) const2251 MallocChecker::getAllocationSite(const ExplodedNode *N, SymbolRef Sym,
2252 CheckerContext &C) const {
2253 const LocationContext *LeakContext = N->getLocationContext();
2254 // Walk the ExplodedGraph backwards and find the first node that referred to
2255 // the tracked symbol.
2256 const ExplodedNode *AllocNode = N;
2257 const MemRegion *ReferenceRegion = nullptr;
2258
2259 while (N) {
2260 ProgramStateRef State = N->getState();
2261 if (!State->get<RegionState>(Sym))
2262 break;
2263
2264 // Find the most recent expression bound to the symbol in the current
2265 // context.
2266 if (!ReferenceRegion) {
2267 if (const MemRegion *MR = C.getLocationRegionIfPostStore(N)) {
2268 SVal Val = State->getSVal(MR);
2269 if (Val.getAsLocSymbol() == Sym) {
2270 const VarRegion* VR = MR->getBaseRegion()->getAs<VarRegion>();
2271 // Do not show local variables belonging to a function other than
2272 // where the error is reported.
2273 if (!VR ||
2274 (VR->getStackFrame() == LeakContext->getStackFrame()))
2275 ReferenceRegion = MR;
2276 }
2277 }
2278 }
2279
2280 // Allocation node, is the last node in the current or parent context in
2281 // which the symbol was tracked.
2282 const LocationContext *NContext = N->getLocationContext();
2283 if (NContext == LeakContext ||
2284 NContext->isParentOf(LeakContext))
2285 AllocNode = N;
2286 N = N->pred_empty() ? nullptr : *(N->pred_begin());
2287 }
2288
2289 return LeakInfo(AllocNode, ReferenceRegion);
2290 }
2291
reportLeak(SymbolRef Sym,ExplodedNode * N,CheckerContext & C) const2292 void MallocChecker::reportLeak(SymbolRef Sym, ExplodedNode *N,
2293 CheckerContext &C) const {
2294
2295 if (!ChecksEnabled[CK_MallocChecker] &&
2296 !ChecksEnabled[CK_NewDeleteLeaksChecker])
2297 return;
2298
2299 const RefState *RS = C.getState()->get<RegionState>(Sym);
2300 assert(RS && "cannot leak an untracked symbol");
2301 AllocationFamily Family = RS->getAllocationFamily();
2302
2303 if (Family == AF_Alloca)
2304 return;
2305
2306 Optional<MallocChecker::CheckKind>
2307 CheckKind = getCheckIfTracked(Family, true);
2308
2309 if (!CheckKind.hasValue())
2310 return;
2311
2312 assert(N);
2313 if (!BT_Leak[*CheckKind]) {
2314 // Leaks should not be reported if they are post-dominated by a sink:
2315 // (1) Sinks are higher importance bugs.
2316 // (2) NoReturnFunctionChecker uses sink nodes to represent paths ending
2317 // with __noreturn functions such as assert() or exit(). We choose not
2318 // to report leaks on such paths.
2319 BT_Leak[*CheckKind].reset(new BugType(CheckNames[*CheckKind], "Memory leak",
2320 categories::MemoryError,
2321 /*SuppressOnSink=*/true));
2322 }
2323
2324 // Most bug reports are cached at the location where they occurred.
2325 // With leaks, we want to unique them by the location where they were
2326 // allocated, and only report a single path.
2327 PathDiagnosticLocation LocUsedForUniqueing;
2328 const ExplodedNode *AllocNode = nullptr;
2329 const MemRegion *Region = nullptr;
2330 std::tie(AllocNode, Region) = getAllocationSite(N, Sym, C);
2331
2332 const Stmt *AllocationStmt = PathDiagnosticLocation::getStmt(AllocNode);
2333 if (AllocationStmt)
2334 LocUsedForUniqueing = PathDiagnosticLocation::createBegin(AllocationStmt,
2335 C.getSourceManager(),
2336 AllocNode->getLocationContext());
2337
2338 SmallString<200> buf;
2339 llvm::raw_svector_ostream os(buf);
2340 if (Region && Region->canPrintPretty()) {
2341 os << "Potential leak of memory pointed to by ";
2342 Region->printPretty(os);
2343 } else {
2344 os << "Potential memory leak";
2345 }
2346
2347 auto R = llvm::make_unique<BugReport>(
2348 *BT_Leak[*CheckKind], os.str(), N, LocUsedForUniqueing,
2349 AllocNode->getLocationContext()->getDecl());
2350 R->markInteresting(Sym);
2351 R->addVisitor(llvm::make_unique<MallocBugVisitor>(Sym, true));
2352 C.emitReport(std::move(R));
2353 }
2354
checkDeadSymbols(SymbolReaper & SymReaper,CheckerContext & C) const2355 void MallocChecker::checkDeadSymbols(SymbolReaper &SymReaper,
2356 CheckerContext &C) const
2357 {
2358 ProgramStateRef state = C.getState();
2359 RegionStateTy OldRS = state->get<RegionState>();
2360 RegionStateTy::Factory &F = state->get_context<RegionState>();
2361
2362 RegionStateTy RS = OldRS;
2363 SmallVector<SymbolRef, 2> Errors;
2364 for (RegionStateTy::iterator I = RS.begin(), E = RS.end(); I != E; ++I) {
2365 if (SymReaper.isDead(I->first)) {
2366 if (I->second.isAllocated() || I->second.isAllocatedOfSizeZero())
2367 Errors.push_back(I->first);
2368 // Remove the dead symbol from the map.
2369 RS = F.remove(RS, I->first);
2370 }
2371 }
2372
2373 if (RS == OldRS) {
2374 // We shouldn't have touched other maps yet.
2375 assert(state->get<ReallocPairs>() ==
2376 C.getState()->get<ReallocPairs>());
2377 assert(state->get<FreeReturnValue>() ==
2378 C.getState()->get<FreeReturnValue>());
2379 return;
2380 }
2381
2382 // Cleanup the Realloc Pairs Map.
2383 ReallocPairsTy RP = state->get<ReallocPairs>();
2384 for (ReallocPairsTy::iterator I = RP.begin(), E = RP.end(); I != E; ++I) {
2385 if (SymReaper.isDead(I->first) ||
2386 SymReaper.isDead(I->second.ReallocatedSym)) {
2387 state = state->remove<ReallocPairs>(I->first);
2388 }
2389 }
2390
2391 // Cleanup the FreeReturnValue Map.
2392 FreeReturnValueTy FR = state->get<FreeReturnValue>();
2393 for (FreeReturnValueTy::iterator I = FR.begin(), E = FR.end(); I != E; ++I) {
2394 if (SymReaper.isDead(I->first) ||
2395 SymReaper.isDead(I->second)) {
2396 state = state->remove<FreeReturnValue>(I->first);
2397 }
2398 }
2399
2400 // Generate leak node.
2401 ExplodedNode *N = C.getPredecessor();
2402 if (!Errors.empty()) {
2403 static CheckerProgramPointTag Tag("MallocChecker", "DeadSymbolsLeak");
2404 N = C.generateNonFatalErrorNode(C.getState(), &Tag);
2405 if (N) {
2406 for (SmallVectorImpl<SymbolRef>::iterator
2407 I = Errors.begin(), E = Errors.end(); I != E; ++I) {
2408 reportLeak(*I, N, C);
2409 }
2410 }
2411 }
2412
2413 C.addTransition(state->set<RegionState>(RS), N);
2414 }
2415
checkPreCall(const CallEvent & Call,CheckerContext & C) const2416 void MallocChecker::checkPreCall(const CallEvent &Call,
2417 CheckerContext &C) const {
2418
2419 if (const CXXDestructorCall *DC = dyn_cast<CXXDestructorCall>(&Call)) {
2420 SymbolRef Sym = DC->getCXXThisVal().getAsSymbol();
2421 if (!Sym || checkDoubleDelete(Sym, C))
2422 return;
2423 }
2424
2425 // We will check for double free in the post visit.
2426 if (const AnyFunctionCall *FC = dyn_cast<AnyFunctionCall>(&Call)) {
2427 const FunctionDecl *FD = FC->getDecl();
2428 if (!FD)
2429 return;
2430
2431 ASTContext &Ctx = C.getASTContext();
2432 if (ChecksEnabled[CK_MallocChecker] &&
2433 (isCMemFunction(FD, Ctx, AF_Malloc, MemoryOperationKind::MOK_Free) ||
2434 isCMemFunction(FD, Ctx, AF_IfNameIndex,
2435 MemoryOperationKind::MOK_Free)))
2436 return;
2437 }
2438
2439 // Check if the callee of a method is deleted.
2440 if (const CXXInstanceCall *CC = dyn_cast<CXXInstanceCall>(&Call)) {
2441 SymbolRef Sym = CC->getCXXThisVal().getAsSymbol();
2442 if (!Sym || checkUseAfterFree(Sym, C, CC->getCXXThisExpr()))
2443 return;
2444 }
2445
2446 // Check arguments for being used after free.
2447 for (unsigned I = 0, E = Call.getNumArgs(); I != E; ++I) {
2448 SVal ArgSVal = Call.getArgSVal(I);
2449 if (ArgSVal.getAs<Loc>()) {
2450 SymbolRef Sym = ArgSVal.getAsSymbol();
2451 if (!Sym)
2452 continue;
2453 if (checkUseAfterFree(Sym, C, Call.getArgExpr(I)))
2454 return;
2455 }
2456 }
2457 }
2458
checkPreStmt(const ReturnStmt * S,CheckerContext & C) const2459 void MallocChecker::checkPreStmt(const ReturnStmt *S,
2460 CheckerContext &C) const {
2461 checkEscapeOnReturn(S, C);
2462 }
2463
2464 // In the CFG, automatic destructors come after the return statement.
2465 // This callback checks for returning memory that is freed by automatic
2466 // destructors, as those cannot be reached in checkPreStmt().
checkEndFunction(const ReturnStmt * S,CheckerContext & C) const2467 void MallocChecker::checkEndFunction(const ReturnStmt *S,
2468 CheckerContext &C) const {
2469 checkEscapeOnReturn(S, C);
2470 }
2471
checkEscapeOnReturn(const ReturnStmt * S,CheckerContext & C) const2472 void MallocChecker::checkEscapeOnReturn(const ReturnStmt *S,
2473 CheckerContext &C) const {
2474 if (!S)
2475 return;
2476
2477 const Expr *E = S->getRetValue();
2478 if (!E)
2479 return;
2480
2481 // Check if we are returning a symbol.
2482 ProgramStateRef State = C.getState();
2483 SVal RetVal = C.getSVal(E);
2484 SymbolRef Sym = RetVal.getAsSymbol();
2485 if (!Sym)
2486 // If we are returning a field of the allocated struct or an array element,
2487 // the callee could still free the memory.
2488 // TODO: This logic should be a part of generic symbol escape callback.
2489 if (const MemRegion *MR = RetVal.getAsRegion())
2490 if (isa<FieldRegion>(MR) || isa<ElementRegion>(MR))
2491 if (const SymbolicRegion *BMR =
2492 dyn_cast<SymbolicRegion>(MR->getBaseRegion()))
2493 Sym = BMR->getSymbol();
2494
2495 // Check if we are returning freed memory.
2496 if (Sym)
2497 checkUseAfterFree(Sym, C, E);
2498 }
2499
2500 // TODO: Blocks should be either inlined or should call invalidate regions
2501 // upon invocation. After that's in place, special casing here will not be
2502 // needed.
checkPostStmt(const BlockExpr * BE,CheckerContext & C) const2503 void MallocChecker::checkPostStmt(const BlockExpr *BE,
2504 CheckerContext &C) const {
2505
2506 // Scan the BlockDecRefExprs for any object the retain count checker
2507 // may be tracking.
2508 if (!BE->getBlockDecl()->hasCaptures())
2509 return;
2510
2511 ProgramStateRef state = C.getState();
2512 const BlockDataRegion *R =
2513 cast<BlockDataRegion>(C.getSVal(BE).getAsRegion());
2514
2515 BlockDataRegion::referenced_vars_iterator I = R->referenced_vars_begin(),
2516 E = R->referenced_vars_end();
2517
2518 if (I == E)
2519 return;
2520
2521 SmallVector<const MemRegion*, 10> Regions;
2522 const LocationContext *LC = C.getLocationContext();
2523 MemRegionManager &MemMgr = C.getSValBuilder().getRegionManager();
2524
2525 for ( ; I != E; ++I) {
2526 const VarRegion *VR = I.getCapturedRegion();
2527 if (VR->getSuperRegion() == R) {
2528 VR = MemMgr.getVarRegion(VR->getDecl(), LC);
2529 }
2530 Regions.push_back(VR);
2531 }
2532
2533 state =
2534 state->scanReachableSymbols<StopTrackingCallback>(Regions).getState();
2535 C.addTransition(state);
2536 }
2537
isReleased(SymbolRef Sym,CheckerContext & C) const2538 bool MallocChecker::isReleased(SymbolRef Sym, CheckerContext &C) const {
2539 assert(Sym);
2540 const RefState *RS = C.getState()->get<RegionState>(Sym);
2541 return (RS && RS->isReleased());
2542 }
2543
suppressDeallocationsInSuspiciousContexts(const CallExpr * CE,CheckerContext & C) const2544 bool MallocChecker::suppressDeallocationsInSuspiciousContexts(
2545 const CallExpr *CE, CheckerContext &C) const {
2546 if (CE->getNumArgs() == 0)
2547 return false;
2548
2549 StringRef FunctionStr = "";
2550 if (const auto *FD = dyn_cast<FunctionDecl>(C.getStackFrame()->getDecl()))
2551 if (const Stmt *Body = FD->getBody())
2552 if (Body->getBeginLoc().isValid())
2553 FunctionStr =
2554 Lexer::getSourceText(CharSourceRange::getTokenRange(
2555 {FD->getBeginLoc(), Body->getBeginLoc()}),
2556 C.getSourceManager(), C.getLangOpts());
2557
2558 // We do not model the Integer Set Library's retain-count based allocation.
2559 if (!FunctionStr.contains("__isl_"))
2560 return false;
2561
2562 ProgramStateRef State = C.getState();
2563
2564 for (const Expr *Arg : CE->arguments())
2565 if (SymbolRef Sym = C.getSVal(Arg).getAsSymbol())
2566 if (const RefState *RS = State->get<RegionState>(Sym))
2567 State = State->set<RegionState>(Sym, RefState::getEscaped(RS));
2568
2569 C.addTransition(State);
2570 return true;
2571 }
2572
checkUseAfterFree(SymbolRef Sym,CheckerContext & C,const Stmt * S) const2573 bool MallocChecker::checkUseAfterFree(SymbolRef Sym, CheckerContext &C,
2574 const Stmt *S) const {
2575
2576 if (isReleased(Sym, C)) {
2577 ReportUseAfterFree(C, S->getSourceRange(), Sym);
2578 return true;
2579 }
2580
2581 return false;
2582 }
2583
checkUseZeroAllocated(SymbolRef Sym,CheckerContext & C,const Stmt * S) const2584 void MallocChecker::checkUseZeroAllocated(SymbolRef Sym, CheckerContext &C,
2585 const Stmt *S) const {
2586 assert(Sym);
2587
2588 if (const RefState *RS = C.getState()->get<RegionState>(Sym)) {
2589 if (RS->isAllocatedOfSizeZero())
2590 ReportUseZeroAllocated(C, RS->getStmt()->getSourceRange(), Sym);
2591 }
2592 else if (C.getState()->contains<ReallocSizeZeroSymbols>(Sym)) {
2593 ReportUseZeroAllocated(C, S->getSourceRange(), Sym);
2594 }
2595 }
2596
checkDoubleDelete(SymbolRef Sym,CheckerContext & C) const2597 bool MallocChecker::checkDoubleDelete(SymbolRef Sym, CheckerContext &C) const {
2598
2599 if (isReleased(Sym, C)) {
2600 ReportDoubleDelete(C, Sym);
2601 return true;
2602 }
2603 return false;
2604 }
2605
2606 // Check if the location is a freed symbolic region.
checkLocation(SVal l,bool isLoad,const Stmt * S,CheckerContext & C) const2607 void MallocChecker::checkLocation(SVal l, bool isLoad, const Stmt *S,
2608 CheckerContext &C) const {
2609 SymbolRef Sym = l.getLocSymbolInBase();
2610 if (Sym) {
2611 checkUseAfterFree(Sym, C, S);
2612 checkUseZeroAllocated(Sym, C, S);
2613 }
2614 }
2615
2616 // If a symbolic region is assumed to NULL (or another constant), stop tracking
2617 // it - assuming that allocation failed on this path.
evalAssume(ProgramStateRef state,SVal Cond,bool Assumption) const2618 ProgramStateRef MallocChecker::evalAssume(ProgramStateRef state,
2619 SVal Cond,
2620 bool Assumption) const {
2621 RegionStateTy RS = state->get<RegionState>();
2622 for (RegionStateTy::iterator I = RS.begin(), E = RS.end(); I != E; ++I) {
2623 // If the symbol is assumed to be NULL, remove it from consideration.
2624 ConstraintManager &CMgr = state->getConstraintManager();
2625 ConditionTruthVal AllocFailed = CMgr.isNull(state, I.getKey());
2626 if (AllocFailed.isConstrainedTrue())
2627 state = state->remove<RegionState>(I.getKey());
2628 }
2629
2630 // Realloc returns 0 when reallocation fails, which means that we should
2631 // restore the state of the pointer being reallocated.
2632 ReallocPairsTy RP = state->get<ReallocPairs>();
2633 for (ReallocPairsTy::iterator I = RP.begin(), E = RP.end(); I != E; ++I) {
2634 // If the symbol is assumed to be NULL, remove it from consideration.
2635 ConstraintManager &CMgr = state->getConstraintManager();
2636 ConditionTruthVal AllocFailed = CMgr.isNull(state, I.getKey());
2637 if (!AllocFailed.isConstrainedTrue())
2638 continue;
2639
2640 SymbolRef ReallocSym = I.getData().ReallocatedSym;
2641 if (const RefState *RS = state->get<RegionState>(ReallocSym)) {
2642 if (RS->isReleased()) {
2643 if (I.getData().Kind == RPToBeFreedAfterFailure)
2644 state = state->set<RegionState>(ReallocSym,
2645 RefState::getAllocated(RS->getAllocationFamily(), RS->getStmt()));
2646 else if (I.getData().Kind == RPDoNotTrackAfterFailure)
2647 state = state->remove<RegionState>(ReallocSym);
2648 else
2649 assert(I.getData().Kind == RPIsFreeOnFailure);
2650 }
2651 }
2652 state = state->remove<ReallocPairs>(I.getKey());
2653 }
2654
2655 return state;
2656 }
2657
mayFreeAnyEscapedMemoryOrIsModeledExplicitly(const CallEvent * Call,ProgramStateRef State,SymbolRef & EscapingSymbol) const2658 bool MallocChecker::mayFreeAnyEscapedMemoryOrIsModeledExplicitly(
2659 const CallEvent *Call,
2660 ProgramStateRef State,
2661 SymbolRef &EscapingSymbol) const {
2662 assert(Call);
2663 EscapingSymbol = nullptr;
2664
2665 // For now, assume that any C++ or block call can free memory.
2666 // TODO: If we want to be more optimistic here, we'll need to make sure that
2667 // regions escape to C++ containers. They seem to do that even now, but for
2668 // mysterious reasons.
2669 if (!(isa<SimpleFunctionCall>(Call) || isa<ObjCMethodCall>(Call)))
2670 return true;
2671
2672 // Check Objective-C messages by selector name.
2673 if (const ObjCMethodCall *Msg = dyn_cast<ObjCMethodCall>(Call)) {
2674 // If it's not a framework call, or if it takes a callback, assume it
2675 // can free memory.
2676 if (!Call->isInSystemHeader() || Call->argumentsMayEscape())
2677 return true;
2678
2679 // If it's a method we know about, handle it explicitly post-call.
2680 // This should happen before the "freeWhenDone" check below.
2681 if (isKnownDeallocObjCMethodName(*Msg))
2682 return false;
2683
2684 // If there's a "freeWhenDone" parameter, but the method isn't one we know
2685 // about, we can't be sure that the object will use free() to deallocate the
2686 // memory, so we can't model it explicitly. The best we can do is use it to
2687 // decide whether the pointer escapes.
2688 if (Optional<bool> FreeWhenDone = getFreeWhenDoneArg(*Msg))
2689 return *FreeWhenDone;
2690
2691 // If the first selector piece ends with "NoCopy", and there is no
2692 // "freeWhenDone" parameter set to zero, we know ownership is being
2693 // transferred. Again, though, we can't be sure that the object will use
2694 // free() to deallocate the memory, so we can't model it explicitly.
2695 StringRef FirstSlot = Msg->getSelector().getNameForSlot(0);
2696 if (FirstSlot.endswith("NoCopy"))
2697 return true;
2698
2699 // If the first selector starts with addPointer, insertPointer,
2700 // or replacePointer, assume we are dealing with NSPointerArray or similar.
2701 // This is similar to C++ containers (vector); we still might want to check
2702 // that the pointers get freed by following the container itself.
2703 if (FirstSlot.startswith("addPointer") ||
2704 FirstSlot.startswith("insertPointer") ||
2705 FirstSlot.startswith("replacePointer") ||
2706 FirstSlot.equals("valueWithPointer")) {
2707 return true;
2708 }
2709
2710 // We should escape receiver on call to 'init'. This is especially relevant
2711 // to the receiver, as the corresponding symbol is usually not referenced
2712 // after the call.
2713 if (Msg->getMethodFamily() == OMF_init) {
2714 EscapingSymbol = Msg->getReceiverSVal().getAsSymbol();
2715 return true;
2716 }
2717
2718 // Otherwise, assume that the method does not free memory.
2719 // Most framework methods do not free memory.
2720 return false;
2721 }
2722
2723 // At this point the only thing left to handle is straight function calls.
2724 const FunctionDecl *FD = cast<SimpleFunctionCall>(Call)->getDecl();
2725 if (!FD)
2726 return true;
2727
2728 ASTContext &ASTC = State->getStateManager().getContext();
2729
2730 // If it's one of the allocation functions we can reason about, we model
2731 // its behavior explicitly.
2732 if (isMemFunction(FD, ASTC))
2733 return false;
2734
2735 // If it's not a system call, assume it frees memory.
2736 if (!Call->isInSystemHeader())
2737 return true;
2738
2739 // White list the system functions whose arguments escape.
2740 const IdentifierInfo *II = FD->getIdentifier();
2741 if (!II)
2742 return true;
2743 StringRef FName = II->getName();
2744
2745 // White list the 'XXXNoCopy' CoreFoundation functions.
2746 // We specifically check these before
2747 if (FName.endswith("NoCopy")) {
2748 // Look for the deallocator argument. We know that the memory ownership
2749 // is not transferred only if the deallocator argument is
2750 // 'kCFAllocatorNull'.
2751 for (unsigned i = 1; i < Call->getNumArgs(); ++i) {
2752 const Expr *ArgE = Call->getArgExpr(i)->IgnoreParenCasts();
2753 if (const DeclRefExpr *DE = dyn_cast<DeclRefExpr>(ArgE)) {
2754 StringRef DeallocatorName = DE->getFoundDecl()->getName();
2755 if (DeallocatorName == "kCFAllocatorNull")
2756 return false;
2757 }
2758 }
2759 return true;
2760 }
2761
2762 // Associating streams with malloced buffers. The pointer can escape if
2763 // 'closefn' is specified (and if that function does free memory),
2764 // but it will not if closefn is not specified.
2765 // Currently, we do not inspect the 'closefn' function (PR12101).
2766 if (FName == "funopen")
2767 if (Call->getNumArgs() >= 4 && Call->getArgSVal(4).isConstant(0))
2768 return false;
2769
2770 // Do not warn on pointers passed to 'setbuf' when used with std streams,
2771 // these leaks might be intentional when setting the buffer for stdio.
2772 // http://stackoverflow.com/questions/2671151/who-frees-setvbuf-buffer
2773 if (FName == "setbuf" || FName =="setbuffer" ||
2774 FName == "setlinebuf" || FName == "setvbuf") {
2775 if (Call->getNumArgs() >= 1) {
2776 const Expr *ArgE = Call->getArgExpr(0)->IgnoreParenCasts();
2777 if (const DeclRefExpr *ArgDRE = dyn_cast<DeclRefExpr>(ArgE))
2778 if (const VarDecl *D = dyn_cast<VarDecl>(ArgDRE->getDecl()))
2779 if (D->getCanonicalDecl()->getName().find("std") != StringRef::npos)
2780 return true;
2781 }
2782 }
2783
2784 // A bunch of other functions which either take ownership of a pointer or
2785 // wrap the result up in a struct or object, meaning it can be freed later.
2786 // (See RetainCountChecker.) Not all the parameters here are invalidated,
2787 // but the Malloc checker cannot differentiate between them. The right way
2788 // of doing this would be to implement a pointer escapes callback.
2789 if (FName == "CGBitmapContextCreate" ||
2790 FName == "CGBitmapContextCreateWithData" ||
2791 FName == "CVPixelBufferCreateWithBytes" ||
2792 FName == "CVPixelBufferCreateWithPlanarBytes" ||
2793 FName == "OSAtomicEnqueue") {
2794 return true;
2795 }
2796
2797 if (FName == "postEvent" &&
2798 FD->getQualifiedNameAsString() == "QCoreApplication::postEvent") {
2799 return true;
2800 }
2801
2802 if (FName == "postEvent" &&
2803 FD->getQualifiedNameAsString() == "QCoreApplication::postEvent") {
2804 return true;
2805 }
2806
2807 if (FName == "connectImpl" &&
2808 FD->getQualifiedNameAsString() == "QObject::connectImpl") {
2809 return true;
2810 }
2811
2812 // Handle cases where we know a buffer's /address/ can escape.
2813 // Note that the above checks handle some special cases where we know that
2814 // even though the address escapes, it's still our responsibility to free the
2815 // buffer.
2816 if (Call->argumentsMayEscape())
2817 return true;
2818
2819 // Otherwise, assume that the function does not free memory.
2820 // Most system calls do not free the memory.
2821 return false;
2822 }
2823
retTrue(const RefState * RS)2824 static bool retTrue(const RefState *RS) {
2825 return true;
2826 }
2827
checkIfNewOrNewArrayFamily(const RefState * RS)2828 static bool checkIfNewOrNewArrayFamily(const RefState *RS) {
2829 return (RS->getAllocationFamily() == AF_CXXNewArray ||
2830 RS->getAllocationFamily() == AF_CXXNew);
2831 }
2832
checkPointerEscape(ProgramStateRef State,const InvalidatedSymbols & Escaped,const CallEvent * Call,PointerEscapeKind Kind) const2833 ProgramStateRef MallocChecker::checkPointerEscape(ProgramStateRef State,
2834 const InvalidatedSymbols &Escaped,
2835 const CallEvent *Call,
2836 PointerEscapeKind Kind) const {
2837 return checkPointerEscapeAux(State, Escaped, Call, Kind, &retTrue);
2838 }
2839
checkConstPointerEscape(ProgramStateRef State,const InvalidatedSymbols & Escaped,const CallEvent * Call,PointerEscapeKind Kind) const2840 ProgramStateRef MallocChecker::checkConstPointerEscape(ProgramStateRef State,
2841 const InvalidatedSymbols &Escaped,
2842 const CallEvent *Call,
2843 PointerEscapeKind Kind) const {
2844 return checkPointerEscapeAux(State, Escaped, Call, Kind,
2845 &checkIfNewOrNewArrayFamily);
2846 }
2847
checkPointerEscapeAux(ProgramStateRef State,const InvalidatedSymbols & Escaped,const CallEvent * Call,PointerEscapeKind Kind,bool (* CheckRefState)(const RefState *)) const2848 ProgramStateRef MallocChecker::checkPointerEscapeAux(ProgramStateRef State,
2849 const InvalidatedSymbols &Escaped,
2850 const CallEvent *Call,
2851 PointerEscapeKind Kind,
2852 bool(*CheckRefState)(const RefState*)) const {
2853 // If we know that the call does not free memory, or we want to process the
2854 // call later, keep tracking the top level arguments.
2855 SymbolRef EscapingSymbol = nullptr;
2856 if (Kind == PSK_DirectEscapeOnCall &&
2857 !mayFreeAnyEscapedMemoryOrIsModeledExplicitly(Call, State,
2858 EscapingSymbol) &&
2859 !EscapingSymbol) {
2860 return State;
2861 }
2862
2863 for (InvalidatedSymbols::const_iterator I = Escaped.begin(),
2864 E = Escaped.end();
2865 I != E; ++I) {
2866 SymbolRef sym = *I;
2867
2868 if (EscapingSymbol && EscapingSymbol != sym)
2869 continue;
2870
2871 if (const RefState *RS = State->get<RegionState>(sym)) {
2872 if ((RS->isAllocated() || RS->isAllocatedOfSizeZero()) &&
2873 CheckRefState(RS)) {
2874 State = State->set<RegionState>(sym, RefState::getEscaped(RS));
2875 }
2876 }
2877 }
2878 return State;
2879 }
2880
findFailedReallocSymbol(ProgramStateRef currState,ProgramStateRef prevState)2881 static SymbolRef findFailedReallocSymbol(ProgramStateRef currState,
2882 ProgramStateRef prevState) {
2883 ReallocPairsTy currMap = currState->get<ReallocPairs>();
2884 ReallocPairsTy prevMap = prevState->get<ReallocPairs>();
2885
2886 for (ReallocPairsTy::iterator I = prevMap.begin(), E = prevMap.end();
2887 I != E; ++I) {
2888 SymbolRef sym = I.getKey();
2889 if (!currMap.lookup(sym))
2890 return sym;
2891 }
2892
2893 return nullptr;
2894 }
2895
isReferenceCountingPointerDestructor(const CXXDestructorDecl * DD)2896 static bool isReferenceCountingPointerDestructor(const CXXDestructorDecl *DD) {
2897 if (const IdentifierInfo *II = DD->getParent()->getIdentifier()) {
2898 StringRef N = II->getName();
2899 if (N.contains_lower("ptr") || N.contains_lower("pointer")) {
2900 if (N.contains_lower("ref") || N.contains_lower("cnt") ||
2901 N.contains_lower("intrusive") || N.contains_lower("shared")) {
2902 return true;
2903 }
2904 }
2905 }
2906 return false;
2907 }
2908
VisitNode(const ExplodedNode * N,BugReporterContext & BRC,BugReport & BR)2909 std::shared_ptr<PathDiagnosticPiece> MallocChecker::MallocBugVisitor::VisitNode(
2910 const ExplodedNode *N, BugReporterContext &BRC, BugReport &BR) {
2911
2912 ProgramStateRef state = N->getState();
2913 ProgramStateRef statePrev = N->getFirstPred()->getState();
2914
2915 const RefState *RS = state->get<RegionState>(Sym);
2916 const RefState *RSPrev = statePrev->get<RegionState>(Sym);
2917
2918 const Stmt *S = PathDiagnosticLocation::getStmt(N);
2919 // When dealing with containers, we sometimes want to give a note
2920 // even if the statement is missing.
2921 if (!S && (!RS || RS->getAllocationFamily() != AF_InnerBuffer))
2922 return nullptr;
2923
2924 const LocationContext *CurrentLC = N->getLocationContext();
2925
2926 // If we find an atomic fetch_add or fetch_sub within the destructor in which
2927 // the pointer was released (before the release), this is likely a destructor
2928 // of a shared pointer.
2929 // Because we don't model atomics, and also because we don't know that the
2930 // original reference count is positive, we should not report use-after-frees
2931 // on objects deleted in such destructors. This can probably be improved
2932 // through better shared pointer modeling.
2933 if (ReleaseDestructorLC) {
2934 if (const auto *AE = dyn_cast<AtomicExpr>(S)) {
2935 AtomicExpr::AtomicOp Op = AE->getOp();
2936 if (Op == AtomicExpr::AO__c11_atomic_fetch_add ||
2937 Op == AtomicExpr::AO__c11_atomic_fetch_sub) {
2938 if (ReleaseDestructorLC == CurrentLC ||
2939 ReleaseDestructorLC->isParentOf(CurrentLC)) {
2940 BR.markInvalid(getTag(), S);
2941 }
2942 }
2943 }
2944 }
2945
2946 // FIXME: We will eventually need to handle non-statement-based events
2947 // (__attribute__((cleanup))).
2948
2949 // Find out if this is an interesting point and what is the kind.
2950 StringRef Msg;
2951 StackHintGeneratorForSymbol *StackHint = nullptr;
2952 SmallString<256> Buf;
2953 llvm::raw_svector_ostream OS(Buf);
2954
2955 if (Mode == Normal) {
2956 if (isAllocated(RS, RSPrev, S)) {
2957 Msg = "Memory is allocated";
2958 StackHint = new StackHintGeneratorForSymbol(Sym,
2959 "Returned allocated memory");
2960 } else if (isReleased(RS, RSPrev, S)) {
2961 const auto Family = RS->getAllocationFamily();
2962 switch (Family) {
2963 case AF_Alloca:
2964 case AF_Malloc:
2965 case AF_CXXNew:
2966 case AF_CXXNewArray:
2967 case AF_IfNameIndex:
2968 Msg = "Memory is released";
2969 StackHint = new StackHintGeneratorForSymbol(Sym,
2970 "Returning; memory was released");
2971 break;
2972 case AF_InnerBuffer: {
2973 const MemRegion *ObjRegion =
2974 allocation_state::getContainerObjRegion(statePrev, Sym);
2975 const auto *TypedRegion = cast<TypedValueRegion>(ObjRegion);
2976 QualType ObjTy = TypedRegion->getValueType();
2977 OS << "Inner buffer of '" << ObjTy.getAsString() << "' ";
2978
2979 if (N->getLocation().getKind() == ProgramPoint::PostImplicitCallKind) {
2980 OS << "deallocated by call to destructor";
2981 StackHint = new StackHintGeneratorForSymbol(Sym,
2982 "Returning; inner buffer was deallocated");
2983 } else {
2984 OS << "reallocated by call to '";
2985 const Stmt *S = RS->getStmt();
2986 if (const auto *MemCallE = dyn_cast<CXXMemberCallExpr>(S)) {
2987 OS << MemCallE->getMethodDecl()->getNameAsString();
2988 } else if (const auto *OpCallE = dyn_cast<CXXOperatorCallExpr>(S)) {
2989 OS << OpCallE->getDirectCallee()->getNameAsString();
2990 } else if (const auto *CallE = dyn_cast<CallExpr>(S)) {
2991 auto &CEMgr = BRC.getStateManager().getCallEventManager();
2992 CallEventRef<> Call = CEMgr.getSimpleCall(CallE, state, CurrentLC);
2993 const auto *D = dyn_cast_or_null<NamedDecl>(Call->getDecl());
2994 OS << (D ? D->getNameAsString() : "unknown");
2995 }
2996 OS << "'";
2997 StackHint = new StackHintGeneratorForSymbol(Sym,
2998 "Returning; inner buffer was reallocated");
2999 }
3000 Msg = OS.str();
3001 break;
3002 }
3003 case AF_None:
3004 llvm_unreachable("Unhandled allocation family!");
3005 }
3006
3007 // See if we're releasing memory while inlining a destructor
3008 // (or one of its callees). This turns on various common
3009 // false positive suppressions.
3010 bool FoundAnyDestructor = false;
3011 for (const LocationContext *LC = CurrentLC; LC; LC = LC->getParent()) {
3012 if (const auto *DD = dyn_cast<CXXDestructorDecl>(LC->getDecl())) {
3013 if (isReferenceCountingPointerDestructor(DD)) {
3014 // This immediately looks like a reference-counting destructor.
3015 // We're bad at guessing the original reference count of the object,
3016 // so suppress the report for now.
3017 BR.markInvalid(getTag(), DD);
3018 } else if (!FoundAnyDestructor) {
3019 assert(!ReleaseDestructorLC &&
3020 "There can be only one release point!");
3021 // Suspect that it's a reference counting pointer destructor.
3022 // On one of the next nodes might find out that it has atomic
3023 // reference counting operations within it (see the code above),
3024 // and if so, we'd conclude that it likely is a reference counting
3025 // pointer destructor.
3026 ReleaseDestructorLC = LC->getStackFrame();
3027 // It is unlikely that releasing memory is delegated to a destructor
3028 // inside a destructor of a shared pointer, because it's fairly hard
3029 // to pass the information that the pointer indeed needs to be
3030 // released into it. So we're only interested in the innermost
3031 // destructor.
3032 FoundAnyDestructor = true;
3033 }
3034 }
3035 }
3036 } else if (isRelinquished(RS, RSPrev, S)) {
3037 Msg = "Memory ownership is transferred";
3038 StackHint = new StackHintGeneratorForSymbol(Sym, "");
3039 } else if (isReallocFailedCheck(RS, RSPrev, S)) {
3040 Mode = ReallocationFailed;
3041 Msg = "Reallocation failed";
3042 StackHint = new StackHintGeneratorForReallocationFailed(Sym,
3043 "Reallocation failed");
3044
3045 if (SymbolRef sym = findFailedReallocSymbol(state, statePrev)) {
3046 // Is it possible to fail two reallocs WITHOUT testing in between?
3047 assert((!FailedReallocSymbol || FailedReallocSymbol == sym) &&
3048 "We only support one failed realloc at a time.");
3049 BR.markInteresting(sym);
3050 FailedReallocSymbol = sym;
3051 }
3052 }
3053
3054 // We are in a special mode if a reallocation failed later in the path.
3055 } else if (Mode == ReallocationFailed) {
3056 assert(FailedReallocSymbol && "No symbol to look for.");
3057
3058 // Is this is the first appearance of the reallocated symbol?
3059 if (!statePrev->get<RegionState>(FailedReallocSymbol)) {
3060 // We're at the reallocation point.
3061 Msg = "Attempt to reallocate memory";
3062 StackHint = new StackHintGeneratorForSymbol(Sym,
3063 "Returned reallocated memory");
3064 FailedReallocSymbol = nullptr;
3065 Mode = Normal;
3066 }
3067 }
3068
3069 if (Msg.empty())
3070 return nullptr;
3071 assert(StackHint);
3072
3073 // Generate the extra diagnostic.
3074 PathDiagnosticLocation Pos;
3075 if (!S) {
3076 assert(RS->getAllocationFamily() == AF_InnerBuffer);
3077 auto PostImplCall = N->getLocation().getAs<PostImplicitCall>();
3078 if (!PostImplCall)
3079 return nullptr;
3080 Pos = PathDiagnosticLocation(PostImplCall->getLocation(),
3081 BRC.getSourceManager());
3082 } else {
3083 Pos = PathDiagnosticLocation(S, BRC.getSourceManager(),
3084 N->getLocationContext());
3085 }
3086
3087 return std::make_shared<PathDiagnosticEventPiece>(Pos, Msg, true, StackHint);
3088 }
3089
printState(raw_ostream & Out,ProgramStateRef State,const char * NL,const char * Sep) const3090 void MallocChecker::printState(raw_ostream &Out, ProgramStateRef State,
3091 const char *NL, const char *Sep) const {
3092
3093 RegionStateTy RS = State->get<RegionState>();
3094
3095 if (!RS.isEmpty()) {
3096 Out << Sep << "MallocChecker :" << NL;
3097 for (RegionStateTy::iterator I = RS.begin(), E = RS.end(); I != E; ++I) {
3098 const RefState *RefS = State->get<RegionState>(I.getKey());
3099 AllocationFamily Family = RefS->getAllocationFamily();
3100 Optional<MallocChecker::CheckKind> CheckKind = getCheckIfTracked(Family);
3101 if (!CheckKind.hasValue())
3102 CheckKind = getCheckIfTracked(Family, true);
3103
3104 I.getKey()->dumpToStream(Out);
3105 Out << " : ";
3106 I.getData().dump(Out);
3107 if (CheckKind.hasValue())
3108 Out << " (" << CheckNames[*CheckKind].getName() << ")";
3109 Out << NL;
3110 }
3111 }
3112 }
3113
3114 namespace clang {
3115 namespace ento {
3116 namespace allocation_state {
3117
3118 ProgramStateRef
markReleased(ProgramStateRef State,SymbolRef Sym,const Expr * Origin)3119 markReleased(ProgramStateRef State, SymbolRef Sym, const Expr *Origin) {
3120 AllocationFamily Family = AF_InnerBuffer;
3121 return State->set<RegionState>(Sym, RefState::getReleased(Family, Origin));
3122 }
3123
3124 } // end namespace allocation_state
3125 } // end namespace ento
3126 } // end namespace clang
3127
3128 // Intended to be used in InnerPointerChecker to register the part of
3129 // MallocChecker connected to it.
registerInnerPointerCheckerAux(CheckerManager & mgr)3130 void ento::registerInnerPointerCheckerAux(CheckerManager &mgr) {
3131 MallocChecker *checker = mgr.getChecker<MallocChecker>();
3132 checker->ChecksEnabled[MallocChecker::CK_InnerPointerChecker] = true;
3133 checker->CheckNames[MallocChecker::CK_InnerPointerChecker] =
3134 mgr.getCurrentCheckName();
3135 }
3136
registerDynamicMemoryModeling(CheckerManager & mgr)3137 void ento::registerDynamicMemoryModeling(CheckerManager &mgr) {
3138 auto *checker = mgr.registerChecker<MallocChecker>();
3139 checker->IsOptimistic = mgr.getAnalyzerOptions().getCheckerBooleanOption(
3140 checker, "Optimistic");
3141 }
3142
shouldRegisterDynamicMemoryModeling(const LangOptions & LO)3143 bool ento::shouldRegisterDynamicMemoryModeling(const LangOptions &LO) {
3144 return true;
3145 }
3146
3147 #define REGISTER_CHECKER(name) \
3148 void ento::register##name(CheckerManager &mgr) { \
3149 MallocChecker *checker = mgr.getChecker<MallocChecker>(); \
3150 checker->ChecksEnabled[MallocChecker::CK_##name] = true; \
3151 checker->CheckNames[MallocChecker::CK_##name] = mgr.getCurrentCheckName(); \
3152 } \
3153 \
3154 bool ento::shouldRegister##name(const LangOptions &LO) { \
3155 return true; \
3156 }
3157
3158 REGISTER_CHECKER(MallocChecker)
3159 REGISTER_CHECKER(NewDeleteChecker)
3160 REGISTER_CHECKER(NewDeleteLeaksChecker)
3161 REGISTER_CHECKER(MismatchedDeallocatorChecker)
3162