1 //=-- lsan_common_mac.cpp -------------------------------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file is a part of LeakSanitizer.
10 // Implementation of common leak checking functionality. Darwin-specific code.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "sanitizer_common/sanitizer_platform.h"
15 #include "sanitizer_common/sanitizer_libc.h"
16 #include "lsan_common.h"
17 
18 #if CAN_SANITIZE_LEAKS && SANITIZER_APPLE
19 
20 #  include <mach/mach.h>
21 #  include <mach/vm_statistics.h>
22 #  include <pthread.h>
23 
24 #  include "lsan_allocator.h"
25 #  include "sanitizer_common/sanitizer_allocator_internal.h"
26 namespace __lsan {
27 
28 enum class SeenRegion {
29   None = 0,
30   AllocOnce = 1 << 0,
31   LibDispatch = 1 << 1,
32   Foundation = 1 << 2,
33   All = AllocOnce | LibDispatch | Foundation
34 };
35 
36 inline SeenRegion operator|(SeenRegion left, SeenRegion right) {
37   return static_cast<SeenRegion>(static_cast<int>(left) |
38                                  static_cast<int>(right));
39 }
40 
41 inline SeenRegion &operator|=(SeenRegion &left, const SeenRegion &right) {
42   left = left | right;
43   return left;
44 }
45 
46 struct RegionScanState {
47   SeenRegion seen_regions = SeenRegion::None;
48   bool in_libdispatch = false;
49 };
50 
51 typedef struct {
52   int disable_counter;
53   u32 current_thread_id;
54   AllocatorCache cache;
55 } thread_local_data_t;
56 
57 static pthread_key_t key;
58 static pthread_once_t key_once = PTHREAD_ONCE_INIT;
59 
60 // The main thread destructor requires the current thread id,
61 // so we can't destroy it until it's been used and reset to invalid tid
62 void restore_tid_data(void *ptr) {
63   thread_local_data_t *data = (thread_local_data_t *)ptr;
64   if (data->current_thread_id != kInvalidTid)
65     pthread_setspecific(key, data);
66 }
67 
68 static void make_tls_key() {
69   CHECK_EQ(pthread_key_create(&key, restore_tid_data), 0);
70 }
71 
72 static thread_local_data_t *get_tls_val(bool alloc) {
73   pthread_once(&key_once, make_tls_key);
74 
75   thread_local_data_t *ptr = (thread_local_data_t *)pthread_getspecific(key);
76   if (ptr == NULL && alloc) {
77     ptr = (thread_local_data_t *)InternalAlloc(sizeof(*ptr));
78     ptr->disable_counter = 0;
79     ptr->current_thread_id = kInvalidTid;
80     ptr->cache = AllocatorCache();
81     pthread_setspecific(key, ptr);
82   }
83 
84   return ptr;
85 }
86 
87 bool DisabledInThisThread() {
88   thread_local_data_t *data = get_tls_val(false);
89   return data ? data->disable_counter > 0 : false;
90 }
91 
92 void DisableInThisThread() { ++get_tls_val(true)->disable_counter; }
93 
94 void EnableInThisThread() {
95   int *disable_counter = &get_tls_val(true)->disable_counter;
96   if (*disable_counter == 0) {
97     DisableCounterUnderflow();
98   }
99   --*disable_counter;
100 }
101 
102 u32 GetCurrentThread() {
103   thread_local_data_t *data = get_tls_val(false);
104   return data ? data->current_thread_id : kInvalidTid;
105 }
106 
107 void SetCurrentThread(u32 tid) { get_tls_val(true)->current_thread_id = tid; }
108 
109 AllocatorCache *GetAllocatorCache() { return &get_tls_val(true)->cache; }
110 
111 LoadedModule *GetLinker() { return nullptr; }
112 
113 // Required on Linux for initialization of TLS behavior, but should not be
114 // required on Darwin.
115 void InitializePlatformSpecificModules() {}
116 
117 // Sections which can't contain contain global pointers. This list errs on the
118 // side of caution to avoid false positives, at the expense of performance.
119 //
120 // Other potentially safe sections include:
121 // __all_image_info, __crash_info, __const, __got, __interpose, __objc_msg_break
122 //
123 // Sections which definitely cannot be included here are:
124 // __objc_data, __objc_const, __data, __bss, __common, __thread_data,
125 // __thread_bss, __thread_vars, __objc_opt_rw, __objc_opt_ptrs
126 static const char *kSkippedSecNames[] = {
127     "__cfstring",       "__la_symbol_ptr",  "__mod_init_func",
128     "__mod_term_func",  "__nl_symbol_ptr",  "__objc_classlist",
129     "__objc_classrefs", "__objc_imageinfo", "__objc_nlclslist",
130     "__objc_protolist", "__objc_selrefs",   "__objc_superrefs"};
131 
132 // Scans global variables for heap pointers.
133 void ProcessGlobalRegions(Frontier *frontier) {
134   for (auto name : kSkippedSecNames)
135     CHECK(internal_strnlen(name, kMaxSegName + 1) <= kMaxSegName);
136 
137   MemoryMappingLayout memory_mapping(false);
138   InternalMmapVector<LoadedModule> modules;
139   modules.reserve(128);
140   memory_mapping.DumpListOfModules(&modules);
141   for (uptr i = 0; i < modules.size(); ++i) {
142     // Even when global scanning is disabled, we still need to scan
143     // system libraries for stashed pointers
144     if (!flags()->use_globals && modules[i].instrumented()) continue;
145 
146     for (const __sanitizer::LoadedModule::AddressRange &range :
147          modules[i].ranges()) {
148       // Sections storing global variables are writable and non-executable
149       if (range.executable || !range.writable) continue;
150 
151       for (auto name : kSkippedSecNames) {
152         if (!internal_strcmp(range.name, name)) continue;
153       }
154 
155       ScanGlobalRange(range.beg, range.end, frontier);
156     }
157   }
158 }
159 
160 void ProcessPlatformSpecificAllocations(Frontier *frontier) {
161   vm_address_t address = 0;
162   kern_return_t err = KERN_SUCCESS;
163 
164   InternalMmapVectorNoCtor<RootRegion> const *root_regions = GetRootRegions();
165 
166   RegionScanState scan_state;
167   while (err == KERN_SUCCESS) {
168     vm_size_t size = 0;
169     unsigned depth = 1;
170     struct vm_region_submap_info_64 info;
171     mach_msg_type_number_t count = VM_REGION_SUBMAP_INFO_COUNT_64;
172     err = vm_region_recurse_64(mach_task_self(), &address, &size, &depth,
173                                (vm_region_info_t)&info, &count);
174 
175     uptr end_address = address + size;
176     if (info.user_tag == VM_MEMORY_OS_ALLOC_ONCE) {
177       // libxpc stashes some pointers in the Kernel Alloc Once page,
178       // make sure not to report those as leaks.
179       scan_state.seen_regions |= SeenRegion::AllocOnce;
180       ScanRangeForPointers(address, end_address, frontier, "GLOBAL",
181                            kReachable);
182     } else if (info.user_tag == VM_MEMORY_FOUNDATION) {
183       // Objective-C block trampolines use the Foundation region.
184       scan_state.seen_regions |= SeenRegion::Foundation;
185       ScanRangeForPointers(address, end_address, frontier, "GLOBAL",
186                            kReachable);
187     } else if (info.user_tag == VM_MEMORY_LIBDISPATCH) {
188       // Dispatch continuations use the libdispatch region. Empirically, there
189       // can be more than one region with this tag, so we'll optimistically
190       // assume that they're continguous. Otherwise, we would need to scan every
191       // region to ensure we find them all.
192       scan_state.in_libdispatch = true;
193       ScanRangeForPointers(address, end_address, frontier, "GLOBAL",
194                            kReachable);
195     } else if (scan_state.in_libdispatch) {
196       scan_state.seen_regions |= SeenRegion::LibDispatch;
197       scan_state.in_libdispatch = false;
198     }
199 
200     // Recursing over the full memory map is very slow, break out
201     // early if we don't need the full iteration.
202     if (scan_state.seen_regions == SeenRegion::All &&
203         !(flags()->use_root_regions && root_regions->size() > 0)) {
204       break;
205     }
206 
207     // This additional root region scan is required on Darwin in order to
208     // detect root regions contained within mmap'd memory regions, because
209     // the Darwin implementation of sanitizer_procmaps traverses images
210     // as loaded by dyld, and not the complete set of all memory regions.
211     //
212     // TODO(fjricci) - remove this once sanitizer_procmaps_mac has the same
213     // behavior as sanitizer_procmaps_linux and traverses all memory regions
214     if (flags()->use_root_regions) {
215       for (uptr i = 0; i < root_regions->size(); i++) {
216         ScanRootRegion(frontier, (*root_regions)[i], address, end_address,
217                        info.protection & kProtectionRead);
218       }
219     }
220 
221     address = end_address;
222   }
223 }
224 
225 // On darwin, we can intercept _exit gracefully, and return a failing exit code
226 // if required at that point. Calling Die() here is undefined behavior and
227 // causes rare race conditions.
228 void HandleLeaks() {}
229 
230 void LockStuffAndStopTheWorld(StopTheWorldCallback callback,
231                               CheckForLeaksParam *argument) {
232   ScopedStopTheWorldLock lock;
233   StopTheWorld(callback, argument);
234 }
235 
236 }  // namespace __lsan
237 
238 #endif // CAN_SANITIZE_LEAKS && SANITIZER_APPLE
239