xref: /freebsd/contrib/llvm-project/compiler-rt/lib/msan/msan.cpp (revision 02e9120893770924227138ba49df1edb3896112a)
1 //===-- msan.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 MemorySanitizer.
10 //
11 // MemorySanitizer runtime.
12 //===----------------------------------------------------------------------===//
13 
14 #include "msan.h"
15 
16 #include "msan_chained_origin_depot.h"
17 #include "msan_origin.h"
18 #include "msan_poisoning.h"
19 #include "msan_report.h"
20 #include "msan_thread.h"
21 #include "sanitizer_common/sanitizer_atomic.h"
22 #include "sanitizer_common/sanitizer_common.h"
23 #include "sanitizer_common/sanitizer_flag_parser.h"
24 #include "sanitizer_common/sanitizer_flags.h"
25 #include "sanitizer_common/sanitizer_interface_internal.h"
26 #include "sanitizer_common/sanitizer_libc.h"
27 #include "sanitizer_common/sanitizer_procmaps.h"
28 #include "sanitizer_common/sanitizer_stackdepot.h"
29 #include "sanitizer_common/sanitizer_stacktrace.h"
30 #include "sanitizer_common/sanitizer_symbolizer.h"
31 #include "ubsan/ubsan_flags.h"
32 #include "ubsan/ubsan_init.h"
33 
34 // ACHTUNG! No system header includes in this file.
35 
36 using namespace __sanitizer;
37 
38 // Globals.
39 static THREADLOCAL int msan_expect_umr = 0;
40 static THREADLOCAL int msan_expected_umr_found = 0;
41 
42 // Function argument shadow. Each argument starts at the next available 8-byte
43 // aligned address.
44 SANITIZER_INTERFACE_ATTRIBUTE
45 THREADLOCAL u64 __msan_param_tls[kMsanParamTlsSize / sizeof(u64)];
46 
47 // Function argument origin. Each argument starts at the same offset as the
48 // corresponding shadow in (__msan_param_tls). Slightly weird, but changing this
49 // would break compatibility with older prebuilt binaries.
50 SANITIZER_INTERFACE_ATTRIBUTE
51 THREADLOCAL u32 __msan_param_origin_tls[kMsanParamTlsSize / sizeof(u32)];
52 
53 SANITIZER_INTERFACE_ATTRIBUTE
54 THREADLOCAL u64 __msan_retval_tls[kMsanRetvalTlsSize / sizeof(u64)];
55 
56 SANITIZER_INTERFACE_ATTRIBUTE
57 THREADLOCAL u32 __msan_retval_origin_tls;
58 
59 SANITIZER_INTERFACE_ATTRIBUTE
60 ALIGNED(16) THREADLOCAL u64 __msan_va_arg_tls[kMsanParamTlsSize / sizeof(u64)];
61 
62 SANITIZER_INTERFACE_ATTRIBUTE
63 ALIGNED(16)
64 THREADLOCAL u32 __msan_va_arg_origin_tls[kMsanParamTlsSize / sizeof(u32)];
65 
66 SANITIZER_INTERFACE_ATTRIBUTE
67 THREADLOCAL u64 __msan_va_arg_overflow_size_tls;
68 
69 SANITIZER_INTERFACE_ATTRIBUTE
70 THREADLOCAL u32 __msan_origin_tls;
71 
72 extern "C" SANITIZER_WEAK_ATTRIBUTE const int __msan_track_origins;
73 
74 int __msan_get_track_origins() {
75   return &__msan_track_origins ? __msan_track_origins : 0;
76 }
77 
78 extern "C" SANITIZER_WEAK_ATTRIBUTE const int __msan_keep_going;
79 
80 namespace __msan {
81 
82 static THREADLOCAL int is_in_symbolizer_or_unwinder;
83 static void EnterSymbolizerOrUnwider() { ++is_in_symbolizer_or_unwinder; }
84 static void ExitSymbolizerOrUnwider() { --is_in_symbolizer_or_unwinder; }
85 bool IsInSymbolizerOrUnwider() { return is_in_symbolizer_or_unwinder; }
86 
87 struct UnwinderScope {
88   UnwinderScope() { EnterSymbolizerOrUnwider(); }
89   ~UnwinderScope() { ExitSymbolizerOrUnwider(); }
90 };
91 
92 static Flags msan_flags;
93 
94 Flags *flags() { return &msan_flags; }
95 
96 int msan_inited = 0;
97 bool msan_init_is_running;
98 
99 int msan_report_count = 0;
100 
101 // Array of stack origins.
102 // FIXME: make it resizable.
103 static const uptr kNumStackOriginDescrs = 1024 * 1024;
104 static const char *StackOriginDescr[kNumStackOriginDescrs];
105 static uptr StackOriginPC[kNumStackOriginDescrs];
106 static atomic_uint32_t NumStackOriginDescrs;
107 
108 void Flags::SetDefaults() {
109 #define MSAN_FLAG(Type, Name, DefaultValue, Description) Name = DefaultValue;
110 #include "msan_flags.inc"
111 #undef MSAN_FLAG
112 }
113 
114 // keep_going is an old name for halt_on_error,
115 // and it has inverse meaning.
116 class FlagHandlerKeepGoing final : public FlagHandlerBase {
117   bool *halt_on_error_;
118 
119  public:
120   explicit FlagHandlerKeepGoing(bool *halt_on_error)
121       : halt_on_error_(halt_on_error) {}
122   bool Parse(const char *value) final {
123     bool tmp;
124     FlagHandler<bool> h(&tmp);
125     if (!h.Parse(value)) return false;
126     *halt_on_error_ = !tmp;
127     return true;
128   }
129   bool Format(char *buffer, uptr size) final {
130     const char *keep_going_str = (*halt_on_error_) ? "false" : "true";
131     return FormatString(buffer, size, keep_going_str);
132   }
133 };
134 
135 static void RegisterMsanFlags(FlagParser *parser, Flags *f) {
136 #define MSAN_FLAG(Type, Name, DefaultValue, Description) \
137   RegisterFlag(parser, #Name, Description, &f->Name);
138 #include "msan_flags.inc"
139 #undef MSAN_FLAG
140 
141   FlagHandlerKeepGoing *fh_keep_going =
142       new (FlagParser::Alloc) FlagHandlerKeepGoing(&f->halt_on_error);
143   parser->RegisterHandler("keep_going", fh_keep_going,
144                           "deprecated, use halt_on_error");
145 }
146 
147 static void InitializeFlags() {
148   SetCommonFlagsDefaults();
149   {
150     CommonFlags cf;
151     cf.CopyFrom(*common_flags());
152     cf.external_symbolizer_path = GetEnv("MSAN_SYMBOLIZER_PATH");
153     cf.malloc_context_size = 20;
154     cf.handle_ioctl = true;
155     // FIXME: test and enable.
156     cf.check_printf = false;
157     cf.intercept_tls_get_addr = true;
158     OverrideCommonFlags(cf);
159   }
160 
161   Flags *f = flags();
162   f->SetDefaults();
163 
164   FlagParser parser;
165   RegisterMsanFlags(&parser, f);
166   RegisterCommonFlags(&parser);
167 
168 #if MSAN_CONTAINS_UBSAN
169   __ubsan::Flags *uf = __ubsan::flags();
170   uf->SetDefaults();
171 
172   FlagParser ubsan_parser;
173   __ubsan::RegisterUbsanFlags(&ubsan_parser, uf);
174   RegisterCommonFlags(&ubsan_parser);
175 #endif
176 
177   // Override from user-specified string.
178   parser.ParseString(__msan_default_options());
179 #if MSAN_CONTAINS_UBSAN
180   const char *ubsan_default_options = __ubsan_default_options();
181   ubsan_parser.ParseString(ubsan_default_options);
182 #endif
183 
184   parser.ParseStringFromEnv("MSAN_OPTIONS");
185 #if MSAN_CONTAINS_UBSAN
186   ubsan_parser.ParseStringFromEnv("UBSAN_OPTIONS");
187 #endif
188 
189   InitializeCommonFlags();
190 
191   if (Verbosity()) ReportUnrecognizedFlags();
192 
193   if (common_flags()->help) parser.PrintFlagDescriptions();
194 
195   // Check if deprecated exit_code MSan flag is set.
196   if (f->exit_code != -1) {
197     if (Verbosity())
198       Printf("MSAN_OPTIONS=exit_code is deprecated! "
199              "Please use MSAN_OPTIONS=exitcode instead.\n");
200     CommonFlags cf;
201     cf.CopyFrom(*common_flags());
202     cf.exitcode = f->exit_code;
203     OverrideCommonFlags(cf);
204   }
205 
206   // Check flag values:
207   if (f->origin_history_size < 0 ||
208       f->origin_history_size > Origin::kMaxDepth) {
209     Printf(
210         "Origin history size invalid: %d. Must be 0 (unlimited) or in [1, %d] "
211         "range.\n",
212         f->origin_history_size, Origin::kMaxDepth);
213     Die();
214   }
215   // Limiting to kStackDepotMaxUseCount / 2 to avoid overflow in
216   // StackDepotHandle::inc_use_count_unsafe.
217   if (f->origin_history_per_stack_limit < 0 ||
218       f->origin_history_per_stack_limit > kStackDepotMaxUseCount / 2) {
219     Printf(
220         "Origin per-stack limit invalid: %d. Must be 0 (unlimited) or in [1, "
221         "%d] range.\n",
222         f->origin_history_per_stack_limit, kStackDepotMaxUseCount / 2);
223     Die();
224   }
225   if (f->store_context_size < 1) f->store_context_size = 1;
226 }
227 
228 void PrintWarningWithOrigin(uptr pc, uptr bp, u32 origin) {
229   if (msan_expect_umr) {
230     // Printf("Expected UMR\n");
231     __msan_origin_tls = origin;
232     msan_expected_umr_found = 1;
233     return;
234   }
235 
236   ++msan_report_count;
237 
238   GET_FATAL_STACK_TRACE_PC_BP(pc, bp);
239 
240   u32 report_origin =
241     (__msan_get_track_origins() && Origin::isValidId(origin)) ? origin : 0;
242   ReportUMR(&stack, report_origin);
243 
244   if (__msan_get_track_origins() && !Origin::isValidId(origin)) {
245     Printf(
246         "  ORIGIN: invalid (%x). Might be a bug in MemorySanitizer origin "
247         "tracking.\n    This could still be a bug in your code, too!\n",
248         origin);
249   }
250 }
251 
252 void UnpoisonParam(uptr n) {
253   internal_memset(__msan_param_tls, 0, n * sizeof(*__msan_param_tls));
254 }
255 
256 // Backup MSan runtime TLS state.
257 // Implementation must be async-signal-safe.
258 // Instances of this class may live on the signal handler stack, and data size
259 // may be an issue.
260 void ScopedThreadLocalStateBackup::Backup() {
261   va_arg_overflow_size_tls = __msan_va_arg_overflow_size_tls;
262 }
263 
264 void ScopedThreadLocalStateBackup::Restore() {
265   // A lame implementation that only keeps essential state and resets the rest.
266   __msan_va_arg_overflow_size_tls = va_arg_overflow_size_tls;
267 
268   internal_memset(__msan_param_tls, 0, sizeof(__msan_param_tls));
269   internal_memset(__msan_retval_tls, 0, sizeof(__msan_retval_tls));
270   internal_memset(__msan_va_arg_tls, 0, sizeof(__msan_va_arg_tls));
271   internal_memset(__msan_va_arg_origin_tls, 0,
272                   sizeof(__msan_va_arg_origin_tls));
273 
274   if (__msan_get_track_origins()) {
275     internal_memset(&__msan_retval_origin_tls, 0,
276                     sizeof(__msan_retval_origin_tls));
277     internal_memset(__msan_param_origin_tls, 0,
278                     sizeof(__msan_param_origin_tls));
279   }
280 }
281 
282 void UnpoisonThreadLocalState() {
283 }
284 
285 const char *GetStackOriginDescr(u32 id, uptr *pc) {
286   CHECK_LT(id, kNumStackOriginDescrs);
287   if (pc) *pc = StackOriginPC[id];
288   return StackOriginDescr[id];
289 }
290 
291 u32 ChainOrigin(u32 id, StackTrace *stack) {
292   MsanThread *t = GetCurrentThread();
293   if (t && t->InSignalHandler())
294     return id;
295 
296   Origin o = Origin::FromRawId(id);
297   stack->tag = StackTrace::TAG_UNKNOWN;
298   Origin chained = Origin::CreateChainedOrigin(o, stack);
299   return chained.raw_id();
300 }
301 
302 // Current implementation separates the 'id_ptr' from the 'descr' and makes
303 // 'descr' constant.
304 // Previous implementation 'descr' is created at compile time and contains
305 // '----' in the beginning.  When we see descr for the first time we replace
306 // '----' with a uniq id and set the origin to (id | (31-th bit)).
307 static inline void SetAllocaOrigin(void *a, uptr size, u32 *id_ptr, char *descr,
308                                    uptr pc) {
309   static const u32 dash = '-';
310   static const u32 first_timer =
311       dash + (dash << 8) + (dash << 16) + (dash << 24);
312   u32 id = *id_ptr;
313   if (id == 0 || id == first_timer) {
314     u32 idx = atomic_fetch_add(&NumStackOriginDescrs, 1, memory_order_relaxed);
315     CHECK_LT(idx, kNumStackOriginDescrs);
316     StackOriginDescr[idx] = descr;
317     StackOriginPC[idx] = pc;
318     id = Origin::CreateStackOrigin(idx).raw_id();
319     *id_ptr = id;
320   }
321   __msan_set_origin(a, size, id);
322 }
323 
324 }  // namespace __msan
325 
326 void __sanitizer::BufferedStackTrace::UnwindImpl(
327     uptr pc, uptr bp, void *context, bool request_fast, u32 max_depth) {
328   using namespace __msan;
329   MsanThread *t = GetCurrentThread();
330   if (!t || !StackTrace::WillUseFastUnwind(request_fast)) {
331     // Block reports from our interceptors during _Unwind_Backtrace.
332     UnwinderScope sym_scope;
333     return Unwind(max_depth, pc, bp, context, t ? t->stack_top() : 0,
334                   t ? t->stack_bottom() : 0, false);
335   }
336   if (StackTrace::WillUseFastUnwind(request_fast))
337     Unwind(max_depth, pc, bp, nullptr, t->stack_top(), t->stack_bottom(), true);
338   else
339     Unwind(max_depth, pc, 0, context, 0, 0, false);
340 }
341 
342 // Interface.
343 
344 using namespace __msan;
345 
346 #define MSAN_MAYBE_WARNING(type, size)              \
347   void __msan_maybe_warning_##size(type s, u32 o) { \
348     GET_CALLER_PC_BP;                               \
349     if (UNLIKELY(s)) {                              \
350       PrintWarningWithOrigin(pc, bp, o);            \
351       if (__msan::flags()->halt_on_error) {         \
352         Printf("Exiting\n");                        \
353         Die();                                      \
354       }                                             \
355     }                                               \
356   }
357 
358 MSAN_MAYBE_WARNING(u8, 1)
359 MSAN_MAYBE_WARNING(u16, 2)
360 MSAN_MAYBE_WARNING(u32, 4)
361 MSAN_MAYBE_WARNING(u64, 8)
362 
363 #define MSAN_MAYBE_STORE_ORIGIN(type, size)                       \
364   void __msan_maybe_store_origin_##size(type s, void *p, u32 o) { \
365     if (UNLIKELY(s)) {                                            \
366       if (__msan_get_track_origins() > 1) {                       \
367         GET_CALLER_PC_BP;                                         \
368         GET_STORE_STACK_TRACE_PC_BP(pc, bp);                      \
369         o = ChainOrigin(o, &stack);                               \
370       }                                                           \
371       *(u32 *)MEM_TO_ORIGIN((uptr)p & ~3UL) = o;                  \
372     }                                                             \
373   }
374 
375 MSAN_MAYBE_STORE_ORIGIN(u8, 1)
376 MSAN_MAYBE_STORE_ORIGIN(u16, 2)
377 MSAN_MAYBE_STORE_ORIGIN(u32, 4)
378 MSAN_MAYBE_STORE_ORIGIN(u64, 8)
379 
380 void __msan_warning() {
381   GET_CALLER_PC_BP;
382   PrintWarningWithOrigin(pc, bp, 0);
383   if (__msan::flags()->halt_on_error) {
384     if (__msan::flags()->print_stats)
385       ReportStats();
386     Printf("Exiting\n");
387     Die();
388   }
389 }
390 
391 void __msan_warning_noreturn() {
392   GET_CALLER_PC_BP;
393   PrintWarningWithOrigin(pc, bp, 0);
394   if (__msan::flags()->print_stats)
395     ReportStats();
396   Printf("Exiting\n");
397   Die();
398 }
399 
400 void __msan_warning_with_origin(u32 origin) {
401   GET_CALLER_PC_BP;
402   PrintWarningWithOrigin(pc, bp, origin);
403   if (__msan::flags()->halt_on_error) {
404     if (__msan::flags()->print_stats)
405       ReportStats();
406     Printf("Exiting\n");
407     Die();
408   }
409 }
410 
411 void __msan_warning_with_origin_noreturn(u32 origin) {
412   GET_CALLER_PC_BP;
413   PrintWarningWithOrigin(pc, bp, origin);
414   if (__msan::flags()->print_stats)
415     ReportStats();
416   Printf("Exiting\n");
417   Die();
418 }
419 
420 static void OnStackUnwind(const SignalContext &sig, const void *,
421                           BufferedStackTrace *stack) {
422   stack->Unwind(StackTrace::GetNextInstructionPc(sig.pc), sig.bp, sig.context,
423                 common_flags()->fast_unwind_on_fatal);
424 }
425 
426 static void MsanOnDeadlySignal(int signo, void *siginfo, void *context) {
427   HandleDeadlySignal(siginfo, context, GetTid(), &OnStackUnwind, nullptr);
428 }
429 
430 static void CheckUnwind() {
431   GET_FATAL_STACK_TRACE_PC_BP(StackTrace::GetCurrentPc(), GET_CURRENT_FRAME());
432   stack.Print();
433 }
434 
435 void __msan_init() {
436   CHECK(!msan_init_is_running);
437   if (msan_inited) return;
438   msan_init_is_running = 1;
439   SanitizerToolName = "MemorySanitizer";
440 
441   AvoidCVE_2016_2143();
442 
443   CacheBinaryName();
444   InitializeFlags();
445 
446   // Install tool-specific callbacks in sanitizer_common.
447   SetCheckUnwindCallback(CheckUnwind);
448 
449   __sanitizer_set_report_path(common_flags()->log_path);
450 
451   InitializeInterceptors();
452   CheckASLR();
453   InitTlsSize();
454   InstallDeadlySignalHandlers(MsanOnDeadlySignal);
455   InstallAtExitHandler(); // Needs __cxa_atexit interceptor.
456 
457   DisableCoreDumperIfNecessary();
458   if (StackSizeIsUnlimited()) {
459     VPrintf(1, "Unlimited stack, doing reexec\n");
460     // A reasonably large stack size. It is bigger than the usual 8Mb, because,
461     // well, the program could have been run with unlimited stack for a reason.
462     SetStackSizeLimitInBytes(32 * 1024 * 1024);
463     ReExec();
464   }
465 
466   __msan_clear_on_return();
467   if (__msan_get_track_origins())
468     VPrintf(1, "msan_track_origins\n");
469   if (!InitShadow(__msan_get_track_origins())) {
470     Printf("FATAL: MemorySanitizer can not mmap the shadow memory.\n");
471     Printf("FATAL: Make sure to compile with -fPIE and to link with -pie.\n");
472     Printf("FATAL: Disabling ASLR is known to cause this error.\n");
473     Printf("FATAL: If running under GDB, try "
474            "'set disable-randomization off'.\n");
475     DumpProcessMap();
476     Die();
477   }
478 
479   Symbolizer::GetOrInit()->AddHooks(EnterSymbolizerOrUnwider,
480                                     ExitSymbolizerOrUnwider);
481 
482   InitializeCoverage(common_flags()->coverage, common_flags()->coverage_dir);
483 
484   MsanTSDInit(MsanTSDDtor);
485 
486   MsanAllocatorInit();
487 
488   MsanThread *main_thread = MsanThread::Create(nullptr, nullptr);
489   SetCurrentThread(main_thread);
490   main_thread->Init();
491 
492 #if MSAN_CONTAINS_UBSAN
493   __ubsan::InitAsPlugin();
494 #endif
495 
496   VPrintf(1, "MemorySanitizer init done\n");
497 
498   msan_init_is_running = 0;
499   msan_inited = 1;
500 }
501 
502 void __msan_set_keep_going(int keep_going) {
503   flags()->halt_on_error = !keep_going;
504 }
505 
506 void __msan_set_expect_umr(int expect_umr) {
507   if (expect_umr) {
508     msan_expected_umr_found = 0;
509   } else if (!msan_expected_umr_found) {
510     GET_CALLER_PC_BP;
511     GET_FATAL_STACK_TRACE_PC_BP(pc, bp);
512     ReportExpectedUMRNotFound(&stack);
513     Die();
514   }
515   msan_expect_umr = expect_umr;
516 }
517 
518 void __msan_print_shadow(const void *x, uptr size) {
519   if (!MEM_IS_APP(x)) {
520     Printf("Not a valid application address: %p\n", x);
521     return;
522   }
523 
524   DescribeMemoryRange(x, size);
525 }
526 
527 void __msan_dump_shadow(const void *x, uptr size) {
528   if (!MEM_IS_APP(x)) {
529     Printf("Not a valid application address: %p\n", x);
530     return;
531   }
532 
533   unsigned char *s = (unsigned char*)MEM_TO_SHADOW(x);
534   Printf("%p[%p]  ", (void *)s, x);
535   for (uptr i = 0; i < size; i++)
536     Printf("%x%x ", s[i] >> 4, s[i] & 0xf);
537   Printf("\n");
538 }
539 
540 sptr __msan_test_shadow(const void *x, uptr size) {
541   if (!MEM_IS_APP(x)) return -1;
542   unsigned char *s = (unsigned char *)MEM_TO_SHADOW((uptr)x);
543   if (__sanitizer::mem_is_zero((const char *)s, size))
544     return -1;
545   // Slow path: loop through again to find the location.
546   for (uptr i = 0; i < size; ++i)
547     if (s[i])
548       return i;
549   return -1;
550 }
551 
552 void __msan_check_mem_is_initialized(const void *x, uptr size) {
553   if (!__msan::flags()->report_umrs) return;
554   sptr offset = __msan_test_shadow(x, size);
555   if (offset < 0)
556     return;
557 
558   GET_CALLER_PC_BP;
559   ReportUMRInsideAddressRange(__func__, x, size, offset);
560   __msan::PrintWarningWithOrigin(pc, bp,
561                                  __msan_get_origin(((const char *)x) + offset));
562   if (__msan::flags()->halt_on_error) {
563     Printf("Exiting\n");
564     Die();
565   }
566 }
567 
568 int __msan_set_poison_in_malloc(int do_poison) {
569   int old = flags()->poison_in_malloc;
570   flags()->poison_in_malloc = do_poison;
571   return old;
572 }
573 
574 int __msan_has_dynamic_component() { return false; }
575 
576 NOINLINE
577 void __msan_clear_on_return() {
578   __msan_param_tls[0] = 0;
579 }
580 
581 void __msan_partial_poison(const void* data, void* shadow, uptr size) {
582   internal_memcpy((void*)MEM_TO_SHADOW((uptr)data), shadow, size);
583 }
584 
585 void __msan_load_unpoisoned(const void *src, uptr size, void *dst) {
586   internal_memcpy(dst, src, size);
587   __msan_unpoison(dst, size);
588 }
589 
590 void __msan_set_origin(const void *a, uptr size, u32 origin) {
591   if (__msan_get_track_origins()) SetOrigin(a, size, origin);
592 }
593 
594 void __msan_set_alloca_origin(void *a, uptr size, char *descr) {
595   SetAllocaOrigin(a, size, reinterpret_cast<u32 *>(descr), descr + 4,
596                   GET_CALLER_PC());
597 }
598 
599 void __msan_set_alloca_origin4(void *a, uptr size, char *descr, uptr pc) {
600   // Intentionally ignore pc and use return address. This function is here for
601   // compatibility, in case program is linked with library instrumented by
602   // older clang.
603   SetAllocaOrigin(a, size, reinterpret_cast<u32 *>(descr), descr + 4,
604                   GET_CALLER_PC());
605 }
606 
607 void __msan_set_alloca_origin_with_descr(void *a, uptr size, u32 *id_ptr,
608                                          char *descr) {
609   SetAllocaOrigin(a, size, id_ptr, descr, GET_CALLER_PC());
610 }
611 
612 void __msan_set_alloca_origin_no_descr(void *a, uptr size, u32 *id_ptr) {
613   SetAllocaOrigin(a, size, id_ptr, nullptr, GET_CALLER_PC());
614 }
615 
616 u32 __msan_chain_origin(u32 id) {
617   GET_CALLER_PC_BP;
618   GET_STORE_STACK_TRACE_PC_BP(pc, bp);
619   return ChainOrigin(id, &stack);
620 }
621 
622 u32 __msan_get_origin(const void *a) {
623   if (!__msan_get_track_origins()) return 0;
624   uptr x = (uptr)a;
625   uptr aligned = x & ~3ULL;
626   uptr origin_ptr = MEM_TO_ORIGIN(aligned);
627   return *(u32*)origin_ptr;
628 }
629 
630 int __msan_origin_is_descendant_or_same(u32 this_id, u32 prev_id) {
631   Origin o = Origin::FromRawId(this_id);
632   while (o.raw_id() != prev_id && o.isChainedOrigin())
633     o = o.getNextChainedOrigin(nullptr);
634   return o.raw_id() == prev_id;
635 }
636 
637 u32 __msan_get_umr_origin() {
638   return __msan_origin_tls;
639 }
640 
641 u16 __sanitizer_unaligned_load16(const uu16 *p) {
642   internal_memcpy(&__msan_retval_tls[0], (void *)MEM_TO_SHADOW((uptr)p),
643                   sizeof(uu16));
644   if (__msan_get_track_origins())
645     __msan_retval_origin_tls = GetOriginIfPoisoned((uptr)p, sizeof(*p));
646   return *p;
647 }
648 u32 __sanitizer_unaligned_load32(const uu32 *p) {
649   internal_memcpy(&__msan_retval_tls[0], (void *)MEM_TO_SHADOW((uptr)p),
650                   sizeof(uu32));
651   if (__msan_get_track_origins())
652     __msan_retval_origin_tls = GetOriginIfPoisoned((uptr)p, sizeof(*p));
653   return *p;
654 }
655 u64 __sanitizer_unaligned_load64(const uu64 *p) {
656   internal_memcpy(&__msan_retval_tls[0], (void *)MEM_TO_SHADOW((uptr)p),
657                   sizeof(uu64));
658   if (__msan_get_track_origins())
659     __msan_retval_origin_tls = GetOriginIfPoisoned((uptr)p, sizeof(*p));
660   return *p;
661 }
662 void __sanitizer_unaligned_store16(uu16 *p, u16 x) {
663   static_assert(sizeof(uu16) == sizeof(u16), "incompatible types");
664   u16 s;
665   internal_memcpy(&s, &__msan_param_tls[1], sizeof(uu16));
666   internal_memcpy((void *)MEM_TO_SHADOW((uptr)p), &s, sizeof(uu16));
667   if (s && __msan_get_track_origins())
668     if (uu32 o = __msan_param_origin_tls[2])
669       SetOriginIfPoisoned((uptr)p, (uptr)&s, sizeof(s), o);
670   *p = x;
671 }
672 void __sanitizer_unaligned_store32(uu32 *p, u32 x) {
673   static_assert(sizeof(uu32) == sizeof(u32), "incompatible types");
674   u32 s;
675   internal_memcpy(&s, &__msan_param_tls[1], sizeof(uu32));
676   internal_memcpy((void *)MEM_TO_SHADOW((uptr)p), &s, sizeof(uu32));
677   if (s && __msan_get_track_origins())
678     if (uu32 o = __msan_param_origin_tls[2])
679       SetOriginIfPoisoned((uptr)p, (uptr)&s, sizeof(s), o);
680   *p = x;
681 }
682 void __sanitizer_unaligned_store64(uu64 *p, u64 x) {
683   u64 s = __msan_param_tls[1];
684   *(uu64 *)MEM_TO_SHADOW((uptr)p) = s;
685   if (s && __msan_get_track_origins())
686     if (uu32 o = __msan_param_origin_tls[2])
687       SetOriginIfPoisoned((uptr)p, (uptr)&s, sizeof(s), o);
688   *p = x;
689 }
690 
691 void __msan_set_death_callback(void (*callback)(void)) {
692   SetUserDieCallback(callback);
693 }
694 
695 void __msan_start_switch_fiber(const void *bottom, uptr size) {
696   MsanThread *t = GetCurrentThread();
697   if (!t) {
698     VReport(1, "__msan_start_switch_fiber called from unknown thread\n");
699     return;
700   }
701   t->StartSwitchFiber((uptr)bottom, size);
702 }
703 
704 void __msan_finish_switch_fiber(const void **bottom_old, uptr *size_old) {
705   MsanThread *t = GetCurrentThread();
706   if (!t) {
707     VReport(1, "__msan_finish_switch_fiber called from unknown thread\n");
708     return;
709   }
710   t->FinishSwitchFiber((uptr *)bottom_old, (uptr *)size_old);
711 
712   internal_memset(__msan_param_tls, 0, sizeof(__msan_param_tls));
713   internal_memset(__msan_retval_tls, 0, sizeof(__msan_retval_tls));
714   internal_memset(__msan_va_arg_tls, 0, sizeof(__msan_va_arg_tls));
715 
716   if (__msan_get_track_origins()) {
717     internal_memset(__msan_param_origin_tls, 0,
718                     sizeof(__msan_param_origin_tls));
719     internal_memset(&__msan_retval_origin_tls, 0,
720                     sizeof(__msan_retval_origin_tls));
721     internal_memset(__msan_va_arg_origin_tls, 0,
722                     sizeof(__msan_va_arg_origin_tls));
723   }
724 }
725 
726 SANITIZER_INTERFACE_WEAK_DEF(const char *, __msan_default_options, void) {
727   return "";
728 }
729 
730 extern "C" {
731 SANITIZER_INTERFACE_ATTRIBUTE
732 void __sanitizer_print_stack_trace() {
733   GET_FATAL_STACK_TRACE_PC_BP(StackTrace::GetCurrentPc(), GET_CURRENT_FRAME());
734   stack.Print();
735 }
736 } // extern "C"
737