libsanitizer/asan/asan_thread.cc

   1 //===-- asan_thread.cc ----------------------------------------------------===//
   2 //
   3 // This file is distributed under the University of Illinois Open Source
   4 // License. See LICENSE.TXT for details.
   5 //
   6 //===----------------------------------------------------------------------===//
   7 //
   8 // This file is a part of AddressSanitizer, an address sanity checker.
   9 //
  10 // Thread-related code.
  11 //===----------------------------------------------------------------------===//
  12 #include "asan_allocator.h"
  13 #include "asan_interceptors.h"
  14 #include "asan_poisoning.h"
  15 #include "asan_stack.h"
  16 #include "asan_thread.h"
  17 #include "asan_mapping.h"
  18 #include "sanitizer_common/sanitizer_common.h"
  19 #include "sanitizer_common/sanitizer_placement_new.h"
  20 #include "sanitizer_common/sanitizer_stackdepot.h"
  21 #include "sanitizer_common/sanitizer_tls_get_addr.h"
  22 #include "lsan/lsan_common.h"
  23
  24 namespace __asan {
  25
  26 // AsanThreadContext implementation.
  27
  28 void AsanThreadContext::OnCreated(void *arg) {
  29   CreateThreadContextArgs *args = static_cast<CreateThreadContextArgs*>(arg);
  30   if (args->stack)
  31     stack_id = StackDepotPut(*args->stack);
  32   thread = args->thread;
  33   thread->set_context(this);
  34 }
  35
  36 void AsanThreadContext::OnFinished() {
  37   // Drop the link to the AsanThread object.
  38   thread = nullptr;
  39 }
  40
  41 // MIPS requires aligned address
  42 static ALIGNED(16) char thread_registry_placeholder[sizeof(ThreadRegistry)];
  43 static ThreadRegistry *asan_thread_registry;
  44
  45 static BlockingMutex mu_for_thread_context(LINKER_INITIALIZED);
  46 static LowLevelAllocator allocator_for_thread_context;
  47
  48 static ThreadContextBase *GetAsanThreadContext(u32 tid) {
  49   BlockingMutexLock lock(&mu_for_thread_context);
  50   return new(allocator_for_thread_context) AsanThreadContext(tid);
  51 }
  52
  53 ThreadRegistry &asanThreadRegistry() {
  54   static bool initialized;
  55   // Don't worry about thread_safety - this should be called when there is
  56   // a single thread.
  57   if (!initialized) {
  58     // Never reuse ASan threads: we store pointer to AsanThreadContext
  59     // in TSD and can't reliably tell when no more TSD destructors will
  60     // be called. It would be wrong to reuse AsanThreadContext for another
  61     // thread before all TSD destructors will be called for it.
  62     asan_thread_registry = new(thread_registry_placeholder) ThreadRegistry(
  63         GetAsanThreadContext, kMaxNumberOfThreads, kMaxNumberOfThreads);
  64     initialized = true;
  65   }
  66   return *asan_thread_registry;
  67 }
  68
  69 AsanThreadContext *GetThreadContextByTidLocked(u32 tid) {
  70   return static_cast<AsanThreadContext *>(
  71       asanThreadRegistry().GetThreadLocked(tid));
  72 }
  73
  74 // AsanThread implementation.
  75
  76 AsanThread *AsanThread::Create(thread_callback_t start_routine, void *arg,
  77                                u32 parent_tid, StackTrace *stack,
  78                                bool detached) {
  79   uptr PageSize = GetPageSizeCached();
  80   uptr size = RoundUpTo(sizeof(AsanThread), PageSize);
  81   AsanThread *thread = (AsanThread*)MmapOrDie(size, __func__);
  82   thread->start_routine_ = start_routine;
  83   thread->arg_ = arg;
  84   AsanThreadContext::CreateThreadContextArgs args = {thread, stack};
  85   asanThreadRegistry().CreateThread(*reinterpret_cast<uptr *>(thread), detached,
  86                                     parent_tid, &args);
  87
  88   return thread;
  89 }
  90
  91 void AsanThread::TSDDtor(void *tsd) {
  92   AsanThreadContext *context = (AsanThreadContext*)tsd;
  93   VReport(1, "T%d TSDDtor\n", context->tid);
  94   if (context->thread)
  95     context->thread->Destroy();
  96 }
  97
  98 void AsanThread::Destroy() {
  99   int tid = this->tid();
 100   VReport(1, "T%d exited\n", tid);
 101
 102   malloc_storage().CommitBack();
 103   if (common_flags()->use_sigaltstack) UnsetAlternateSignalStack();
 104   asanThreadRegistry().FinishThread(tid);
 105   FlushToDeadThreadStats(&stats_);
 106   // We also clear the shadow on thread destruction because
 107   // some code may still be executing in later TSD destructors
 108   // and we don't want it to have any poisoned stack.
 109   ClearShadowForThreadStackAndTLS();
 110   DeleteFakeStack(tid);
 111   uptr size = RoundUpTo(sizeof(AsanThread), GetPageSizeCached());
 112   UnmapOrDie(this, size);
 113   DTLS_Destroy();
 114 }
 115
 116 void AsanThread::StartSwitchFiber(FakeStack **fake_stack_save, uptr bottom,
 117                                   uptr size) {
 118   if (atomic_load(&stack_switching_, memory_order_relaxed)) {
 119     Report("ERROR: starting fiber switch while in fiber switch\n");
 120     Die();
 121   }
 122
 123   next_stack_bottom_ = bottom;
 124   next_stack_top_ = bottom + size;
 125   atomic_store(&stack_switching_, 1, memory_order_release);
 126
 127   FakeStack *current_fake_stack = fake_stack_;
 128   if (fake_stack_save)
 129     *fake_stack_save = fake_stack_;
 130   fake_stack_ = nullptr;
 131   SetTLSFakeStack(nullptr);
 132   // if fake_stack_save is null, the fiber will die, delete the fakestack
 133   if (!fake_stack_save && current_fake_stack)
 134     current_fake_stack->Destroy(this->tid());
 135 }
 136
 137 void AsanThread::FinishSwitchFiber(FakeStack *fake_stack_save,
 138                                    uptr *bottom_old,
 139                                    uptr *size_old) {
 140   if (!atomic_load(&stack_switching_, memory_order_relaxed)) {
 141     Report("ERROR: finishing a fiber switch that has not started\n");
 142     Die();
 143   }
 144
 145   if (fake_stack_save) {
 146     SetTLSFakeStack(fake_stack_save);
 147     fake_stack_ = fake_stack_save;
 148   }
 149
 150   if (bottom_old)
 151     *bottom_old = stack_bottom_;
 152   if (size_old)
 153     *size_old = stack_top_ - stack_bottom_;
 154   stack_bottom_ = next_stack_bottom_;
 155   stack_top_ = next_stack_top_;
 156   atomic_store(&stack_switching_, 0, memory_order_release);
 157   next_stack_top_ = 0;
 158   next_stack_bottom_ = 0;
 159 }
 160
 161 inline AsanThread::StackBounds AsanThread::GetStackBounds() const {
 162   if (!atomic_load(&stack_switching_, memory_order_acquire)) {
 163     // Make sure the stack bounds are fully initialized.
 164     if (stack_bottom_ >= stack_top_) return {0, 0};
 165     return {stack_bottom_, stack_top_};
 166   }
 167   char local;
 168   const uptr cur_stack = (uptr)&local;
 169   // Note: need to check next stack first, because FinishSwitchFiber
 170   // may be in process of overwriting stack_top_/bottom_. But in such case
 171   // we are already on the next stack.
 172   if (cur_stack >= next_stack_bottom_ && cur_stack < next_stack_top_)
 173     return {next_stack_bottom_, next_stack_top_};
 174   return {stack_bottom_, stack_top_};
 175 }
 176
 177 uptr AsanThread::stack_top() {
 178   return GetStackBounds().top;
 179 }
 180
 181 uptr AsanThread::stack_bottom() {
 182   return GetStackBounds().bottom;
 183 }
 184
 185 uptr AsanThread::stack_size() {
 186   const auto bounds = GetStackBounds();
 187   return bounds.top - bounds.bottom;
 188 }
 189
 190 // We want to create the FakeStack lazyly on the first use, but not eralier
 191 // than the stack size is known and the procedure has to be async-signal safe.
 192 FakeStack *AsanThread::AsyncSignalSafeLazyInitFakeStack() {
 193   uptr stack_size = this->stack_size();
 194   if (stack_size == 0)  // stack_size is not yet available, don't use FakeStack.
 195     return nullptr;
 196   uptr old_val = 0;
 197   // fake_stack_ has 3 states:
 198   // 0   -- not initialized
 199   // 1   -- being initialized
 200   // ptr -- initialized
 201   // This CAS checks if the state was 0 and if so changes it to state 1,
 202   // if that was successful, it initializes the pointer.
 203   if (atomic_compare_exchange_strong(
 204       reinterpret_cast<atomic_uintptr_t *>(&fake_stack_), &old_val, 1UL,
 205       memory_order_relaxed)) {
 206     uptr stack_size_log = Log2(RoundUpToPowerOfTwo(stack_size));
 207     CHECK_LE(flags()->min_uar_stack_size_log, flags()->max_uar_stack_size_log);
 208     stack_size_log =
 209         Min(stack_size_log, static_cast<uptr>(flags()->max_uar_stack_size_log));
 210     stack_size_log =
 211         Max(stack_size_log, static_cast<uptr>(flags()->min_uar_stack_size_log));
 212     fake_stack_ = FakeStack::Create(stack_size_log);
 213     SetTLSFakeStack(fake_stack_);
 214     return fake_stack_;
 215   }
 216   return nullptr;
 217 }
 218
 219 void AsanThread::Init(const InitOptions *options) {
 220   next_stack_top_ = next_stack_bottom_ = 0;
 221   atomic_store(&stack_switching_, false, memory_order_release);
 222   fake_stack_ = nullptr;  // Will be initialized lazily if needed.
 223   CHECK_EQ(this->stack_size(), 0U);
 224   SetThreadStackAndTls(options);
 225   CHECK_GT(this->stack_size(), 0U);
 226   CHECK(AddrIsInMem(stack_bottom_));
 227   CHECK(AddrIsInMem(stack_top_ - 1));
 228   ClearShadowForThreadStackAndTLS();
 229   int local = 0;
 230   VReport(1, "T%d: stack [%p,%p) size 0x%zx; local=%p\n", tid(),
 231           (void *)stack_bottom_, (void *)stack_top_, stack_top_ - stack_bottom_,
 232           &local);
 233 }
 234
 235 // Fuchsia doesn't use ThreadStart.
 236 // asan_fuchsia.c defines CreateMainThread and SetThreadStackAndTls.
 237 #if !SANITIZER_FUCHSIA
 238
 239 thread_return_t AsanThread::ThreadStart(
 240     tid_t os_id, atomic_uintptr_t *signal_thread_is_registered) {
 241   Init();
 242   asanThreadRegistry().StartThread(tid(), os_id, /*workerthread*/ false,
 243                                    nullptr);
 244   if (signal_thread_is_registered)
 245     atomic_store(signal_thread_is_registered, 1, memory_order_release);
 246
 247   if (common_flags()->use_sigaltstack) SetAlternateSignalStack();
 248
 249   if (!start_routine_) {
 250     // start_routine_ == 0 if we're on the main thread or on one of the
 251     // OS X libdispatch worker threads. But nobody is supposed to call
 252     // ThreadStart() for the worker threads.
 253     CHECK_EQ(tid(), 0);
 254     return 0;
 255   }
 256
 257   thread_return_t res = start_routine_(arg_);
 258
 259   // On POSIX systems we defer this to the TSD destructor. LSan will consider
 260   // the thread's memory as non-live from the moment we call Destroy(), even
 261   // though that memory might contain pointers to heap objects which will be
 262   // cleaned up by a user-defined TSD destructor. Thus, calling Destroy() before
 263   // the TSD destructors have run might cause false positives in LSan.
 264   if (!SANITIZER_POSIX)
 265     this->Destroy();
 266
 267   return res;
 268 }
 269
 270 AsanThread *CreateMainThread() {
 271   AsanThread *main_thread = AsanThread::Create(
 272       /* start_routine */ nullptr, /* arg */ nullptr, /* parent_tid */ 0,
 273       /* stack */ nullptr, /* detached */ true);
 274   SetCurrentThread(main_thread);
 275   main_thread->ThreadStart(internal_getpid(),
 276                            /* signal_thread_is_registered */ nullptr);
 277   return main_thread;
 278 }
 279
 280 // This implementation doesn't use the argument, which is just passed down
 281 // from the caller of Init (which see, above).  It's only there to support
 282 // OS-specific implementations that need more information passed through.
 283 void AsanThread::SetThreadStackAndTls(const InitOptions *options) {
 284   DCHECK_EQ(options, nullptr);
 285   uptr tls_size = 0;
 286   uptr stack_size = 0;
 287   GetThreadStackAndTls(tid() == 0, const_cast<uptr *>(&stack_bottom_),
 288                        const_cast<uptr *>(&stack_size), &tls_begin_, &tls_size);
 289   stack_top_ = stack_bottom_ + stack_size;
 290   tls_end_ = tls_begin_ + tls_size;
 291   dtls_ = DTLS_Get();
 292
 293   int local;
 294   CHECK(AddrIsInStack((uptr)&local));
 295 }
 296
 297 #endif  // !SANITIZER_FUCHSIA
 298
 299 void AsanThread::ClearShadowForThreadStackAndTLS() {
 300   PoisonShadow(stack_bottom_, stack_top_ - stack_bottom_, 0);
 301   if (tls_begin_ != tls_end_)
 302     PoisonShadow(tls_begin_, tls_end_ - tls_begin_, 0);
 303 }
 304
 305 bool AsanThread::GetStackFrameAccessByAddr(uptr addr,
 306                                            StackFrameAccess *access) {
 307   uptr bottom = 0;
 308   if (AddrIsInStack(addr)) {
 309     bottom = stack_bottom();
 310   } else if (has_fake_stack()) {
 311     bottom = fake_stack()->AddrIsInFakeStack(addr);
 312     CHECK(bottom);
 313     access->offset = addr - bottom;
 314     access->frame_pc = ((uptr*)bottom)[2];
 315     access->frame_descr = (const char *)((uptr*)bottom)[1];
 316     return true;
 317   }
 318   uptr aligned_addr = RoundDownTo(addr, SANITIZER_WORDSIZE / 8);  // align addr.
 319   uptr mem_ptr = RoundDownTo(aligned_addr, SHADOW_GRANULARITY);
 320   u8 *shadow_ptr = (u8*)MemToShadow(aligned_addr);
 321   u8 *shadow_bottom = (u8*)MemToShadow(bottom);
 322
 323   while (shadow_ptr >= shadow_bottom &&
 324          *shadow_ptr != kAsanStackLeftRedzoneMagic) {
 325     shadow_ptr--;
 326     mem_ptr -= SHADOW_GRANULARITY;
 327   }
 328
 329   while (shadow_ptr >= shadow_bottom &&
 330          *shadow_ptr == kAsanStackLeftRedzoneMagic) {
 331     shadow_ptr--;
 332     mem_ptr -= SHADOW_GRANULARITY;
 333   }
 334
 335   if (shadow_ptr < shadow_bottom) {
 336     return false;
 337   }
 338
 339   uptr* ptr = (uptr*)(mem_ptr + SHADOW_GRANULARITY);
 340   CHECK(ptr[0] == kCurrentStackFrameMagic);
 341   access->offset = addr - (uptr)ptr;
 342   access->frame_pc = ptr[2];
 343   access->frame_descr = (const char*)ptr[1];
 344   return true;
 345 }
 346
 347 uptr AsanThread::GetStackVariableShadowStart(uptr addr) {
 348   uptr bottom = 0;
 349   if (AddrIsInStack(addr)) {
 350     bottom = stack_bottom();
 351   } else if (has_fake_stack()) {
 352     bottom = fake_stack()->AddrIsInFakeStack(addr);
 353     CHECK(bottom);
 354   } else
 355     return 0;
 356
 357   uptr aligned_addr = RoundDownTo(addr, SANITIZER_WORDSIZE / 8);  // align addr.
 358   u8 *shadow_ptr = (u8*)MemToShadow(aligned_addr);
 359   u8 *shadow_bottom = (u8*)MemToShadow(bottom);
 360
 361   while (shadow_ptr >= shadow_bottom &&
 362          (*shadow_ptr != kAsanStackLeftRedzoneMagic &&
 363           *shadow_ptr != kAsanStackMidRedzoneMagic &&
 364           *shadow_ptr != kAsanStackRightRedzoneMagic))
 365     shadow_ptr--;
 366
 367   return (uptr)shadow_ptr + 1;
 368 }
 369
 370 bool AsanThread::AddrIsInStack(uptr addr) {
 371   const auto bounds = GetStackBounds();
 372   return addr >= bounds.bottom && addr < bounds.top;
 373 }
 374
 375 static bool ThreadStackContainsAddress(ThreadContextBase *tctx_base,
 376                                        void *addr) {
 377   AsanThreadContext *tctx = static_cast<AsanThreadContext*>(tctx_base);
 378   AsanThread *t = tctx->thread;
 379   if (!t) return false;
 380   if (t->AddrIsInStack((uptr)addr)) return true;
 381   if (t->has_fake_stack() && t->fake_stack()->AddrIsInFakeStack((uptr)addr))
 382     return true;
 383   return false;
 384 }
 385
 386 AsanThread *GetCurrentThread() {
 387   AsanThreadContext *context =
 388       reinterpret_cast<AsanThreadContext *>(AsanTSDGet());
 389   if (!context) {
 390     if (SANITIZER_ANDROID) {
 391       // On Android, libc constructor is called _after_ asan_init, and cleans up
 392       // TSD. Try to figure out if this is still the main thread by the stack
 393       // address. We are not entirely sure that we have correct main thread
 394       // limits, so only do this magic on Android, and only if the found thread
 395       // is the main thread.
 396       AsanThreadContext *tctx = GetThreadContextByTidLocked(0);
 397       if (tctx && ThreadStackContainsAddress(tctx, &context)) {
 398         SetCurrentThread(tctx->thread);
 399         return tctx->thread;
 400       }
 401     }
 402     return nullptr;
 403   }
 404   return context->thread;
 405 }
 406
 407 void SetCurrentThread(AsanThread *t) {
 408   CHECK(t->context());
 409   VReport(2, "SetCurrentThread: %p for thread %p\n", t->context(),
 410           (void *)GetThreadSelf());
 411   // Make sure we do not reset the current AsanThread.
 412   CHECK_EQ(0, AsanTSDGet());
 413   AsanTSDSet(t->context());
 414   CHECK_EQ(t->context(), AsanTSDGet());
 415 }
 416
 417 u32 GetCurrentTidOrInvalid() {
 418   AsanThread *t = GetCurrentThread();
 419   return t ? t->tid() : kInvalidTid;
 420 }
 421
 422 AsanThread *FindThreadByStackAddress(uptr addr) {
 423   asanThreadRegistry().CheckLocked();
 424   AsanThreadContext *tctx = static_cast<AsanThreadContext *>(
 425       asanThreadRegistry().FindThreadContextLocked(ThreadStackContainsAddress,
 426                                                    (void *)addr));
 427   return tctx ? tctx->thread : nullptr;
 428 }
 429
 430 void EnsureMainThreadIDIsCorrect() {
 431   AsanThreadContext *context =
 432       reinterpret_cast<AsanThreadContext *>(AsanTSDGet());
 433   if (context && (context->tid == 0))
 434     context->os_id = GetTid();
 435 }
 436
 437 __asan::AsanThread *GetAsanThreadByOsIDLocked(tid_t os_id) {
 438   __asan::AsanThreadContext *context = static_cast<__asan::AsanThreadContext *>(
 439       __asan::asanThreadRegistry().FindThreadContextByOsIDLocked(os_id));
 440   if (!context) return nullptr;
 441   return context->thread;
 442 }
 443 } // namespace __asan
 444
 445 // --- Implementation of LSan-specific functions --- {{{1
 446 namespace __lsan {
 447 bool GetThreadRangesLocked(tid_t os_id, uptr *stack_begin, uptr *stack_end,
 448                            uptr *tls_begin, uptr *tls_end, uptr *cache_begin,
 449                            uptr *cache_end, DTLS **dtls) {
 450   __asan::AsanThread *t = __asan::GetAsanThreadByOsIDLocked(os_id);
 451   if (!t) return false;
 452   *stack_begin = t->stack_bottom();
 453   *stack_end = t->stack_top();
 454   *tls_begin = t->tls_begin();
 455   *tls_end = t->tls_end();
 456   // ASan doesn't keep allocator caches in TLS, so these are unused.
 457   *cache_begin = 0;
 458   *cache_end = 0;
 459   *dtls = t->dtls();
 460   return true;
 461 }
 462
 463 void ForEachExtraStackRange(tid_t os_id, RangeIteratorCallback callback,
 464                             void *arg) {
 465   __asan::AsanThread *t = __asan::GetAsanThreadByOsIDLocked(os_id);
 466   if (t && t->has_fake_stack())
 467     t->fake_stack()->ForEachFakeFrame(callback, arg);
 468 }
 469
 470 void LockThreadRegistry() {
 471   __asan::asanThreadRegistry().Lock();
 472 }
 473
 474 void UnlockThreadRegistry() {
 475   __asan::asanThreadRegistry().Unlock();
 476 }
 477
 478 void EnsureMainThreadIDIsCorrect() {
 479   __asan::EnsureMainThreadIDIsCorrect();
 480 }
 481 } // namespace __lsan
 482
 483 // ---------------------- Interface ---------------- {{{1
 484 using namespace __asan;  // NOLINT
 485
 486 extern "C" {
 487 SANITIZER_INTERFACE_ATTRIBUTE
 488 void __sanitizer_start_switch_fiber(void **fakestacksave, const void *bottom,
 489                                     uptr size) {
 490   AsanThread *t = GetCurrentThread();
 491   if (!t) {
 492     VReport(1, "__asan_start_switch_fiber called from unknown thread\n");
 493     return;
 494   }
 495   t->StartSwitchFiber((FakeStack**)fakestacksave, (uptr)bottom, size);
 496 }
 497
 498 SANITIZER_INTERFACE_ATTRIBUTE
 499 void __sanitizer_finish_switch_fiber(void* fakestack,
 500                                      const void **bottom_old,
 501                                      uptr *size_old) {
 502   AsanThread *t = GetCurrentThread();
 503   if (!t) {
 504     VReport(1, "__asan_finish_switch_fiber called from unknown thread\n");
 505     return;
 506   }
 507   t->FinishSwitchFiber((FakeStack*)fakestack,
 508                        (uptr*)bottom_old,
 509                        (uptr*)size_old);
 510 }
 511 }