compiler-rt/lib/hwasan/hwasan_thread.cpp

   1
   2 #include "hwasan_thread.h"
   3
   4 #include "hwasan.h"
   5 #include "hwasan_interface_internal.h"
   6 #include "hwasan_mapping.h"
   7 #include "hwasan_poisoning.h"
   8 #include "sanitizer_common/sanitizer_atomic.h"
   9 #include "sanitizer_common/sanitizer_file.h"
  10 #include "sanitizer_common/sanitizer_placement_new.h"
  11 #include "sanitizer_common/sanitizer_tls_get_addr.h"
  12
  13 namespace __hwasan {
  14
  15 static u32 RandomSeed() {
  16   u32 seed;
  17   do {
  18     if (UNLIKELY(!GetRandom(reinterpret_cast<void *>(&seed), sizeof(seed),
  19                             /*blocking=*/false))) {
  20       seed = static_cast<u32>(
  21           (NanoTime() >> 12) ^
  22           (reinterpret_cast<uptr>(__builtin_frame_address(0)) >> 4));
  23     }
  24   } while (!seed);
  25   return seed;
  26 }
  27
  28 void Thread::InitRandomState() {
  29   random_state_ = flags()->random_tags ? RandomSeed() : unique_id_;
  30   random_state_inited_ = true;
  31
  32   // Push a random number of zeros onto the ring buffer so that the first stack
  33   // tag base will be random.
  34   for (tag_t i = 0, e = GenerateRandomTag(); i != e; ++i)
  35     stack_allocations_->push(0);
  36 }
  37
  38 void Thread::Init(uptr stack_buffer_start, uptr stack_buffer_size,
  39                   const InitState *state) {
  40   CHECK_EQ(0, unique_id_);  // try to catch bad stack reuse
  41   CHECK_EQ(0, stack_top_);
  42   CHECK_EQ(0, stack_bottom_);
  43
  44   static atomic_uint64_t unique_id;
  45   unique_id_ = atomic_fetch_add(&unique_id, 1, memory_order_relaxed);
  46
  47   if (auto sz = flags()->heap_history_size)
  48     heap_allocations_ = HeapAllocationsRingBuffer::New(sz);
  49
  50 #if !SANITIZER_FUCHSIA
  51   // Do not initialize the stack ring buffer just yet on Fuchsia. Threads will
  52   // be initialized before we enter the thread itself, so we will instead call
  53   // this later.
  54   InitStackRingBuffer(stack_buffer_start, stack_buffer_size);
  55 #endif
  56   InitStackAndTls(state);
  57 }
  58
  59 void Thread::InitStackRingBuffer(uptr stack_buffer_start,
  60                                  uptr stack_buffer_size) {
  61   HwasanTSDThreadInit();  // Only needed with interceptors.
  62   uptr *ThreadLong = GetCurrentThreadLongPtr();
  63   // The following implicitly sets (this) as the current thread.
  64   stack_allocations_ = new (ThreadLong)
  65       StackAllocationsRingBuffer((void *)stack_buffer_start, stack_buffer_size);
  66   // Check that it worked.
  67   CHECK_EQ(GetCurrentThread(), this);
  68
  69   // ScopedTaggingDisable needs GetCurrentThread to be set up.
  70   ScopedTaggingDisabler disabler;
  71
  72   if (stack_bottom_) {
  73     int local;
  74     CHECK(AddrIsInStack((uptr)&local));
  75     CHECK(MemIsApp(stack_bottom_));
  76     CHECK(MemIsApp(stack_top_ - 1));
  77   }
  78
  79   if (flags()->verbose_threads) {
  80     if (IsMainThread()) {
  81       Printf("sizeof(Thread): %zd sizeof(HeapRB): %zd sizeof(StackRB): %zd\n",
  82              sizeof(Thread), heap_allocations_->SizeInBytes(),
  83              stack_allocations_->size() * sizeof(uptr));
  84     }
  85     Print("Creating  : ");
  86   }
  87 }
  88
  89 void Thread::ClearShadowForThreadStackAndTLS() {
  90   if (stack_top_ != stack_bottom_)
  91     TagMemory(stack_bottom_, stack_top_ - stack_bottom_, 0);
  92   if (tls_begin_ != tls_end_)
  93     TagMemory(tls_begin_, tls_end_ - tls_begin_, 0);
  94 }
  95
  96 void Thread::Destroy() {
  97   if (flags()->verbose_threads)
  98     Print("Destroying: ");
  99   AllocatorSwallowThreadLocalCache(allocator_cache());
 100   ClearShadowForThreadStackAndTLS();
 101   if (heap_allocations_)
 102     heap_allocations_->Delete();
 103   DTLS_Destroy();
 104   // Unregister this as the current thread.
 105   // Instrumented code can not run on this thread from this point onwards, but
 106   // malloc/free can still be served. Glibc may call free() very late, after all
 107   // TSD destructors are done.
 108   CHECK_EQ(GetCurrentThread(), this);
 109   *GetCurrentThreadLongPtr() = 0;
 110 }
 111
 112 void Thread::Print(const char *Prefix) {
 113   Printf("%sT%zd %p stack: [%p,%p) sz: %zd tls: [%p,%p)\n", Prefix, unique_id_,
 114          (void *)this, stack_bottom(), stack_top(),
 115          stack_top() - stack_bottom(), tls_begin(), tls_end());
 116 }
 117
 118 static u32 xorshift(u32 state) {
 119   state ^= state << 13;
 120   state ^= state >> 17;
 121   state ^= state << 5;
 122   return state;
 123 }
 124
 125 // Generate a (pseudo-)random non-zero tag.
 126 tag_t Thread::GenerateRandomTag(uptr num_bits) {
 127   DCHECK_GT(num_bits, 0);
 128   if (tagging_disabled_)
 129     return 0;
 130   tag_t tag;
 131   const uptr tag_mask = (1ULL << num_bits) - 1;
 132   do {
 133     if (flags()->random_tags) {
 134       if (!random_buffer_) {
 135         EnsureRandomStateInited();
 136         random_buffer_ = random_state_ = xorshift(random_state_);
 137       }
 138       CHECK(random_buffer_);
 139       tag = random_buffer_ & tag_mask;
 140       random_buffer_ >>= num_bits;
 141     } else {
 142       EnsureRandomStateInited();
 143       random_state_ += 1;
 144       tag = random_state_ & tag_mask;
 145     }
 146   } while (!tag);
 147   return tag;
 148 }
 149
 150 } // namespace __hwasan