1 
2 #include "hwasan.h"
3 #include "hwasan_mapping.h"
4 #include "hwasan_thread.h"
5 #include "hwasan_poisoning.h"
6 #include "hwasan_interface_internal.h"
7 
8 #include "sanitizer_common/sanitizer_file.h"
9 #include "sanitizer_common/sanitizer_placement_new.h"
10 #include "sanitizer_common/sanitizer_tls_get_addr.h"
11 
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 
31   // Push a random number of zeros onto the ring buffer so that the first stack
32   // tag base will be random.
33   for (tag_t i = 0, e = GenerateRandomTag(); i != e; ++i)
34     stack_allocations_->push(0);
35 }
36 
37 void Thread::Init(uptr stack_buffer_start, uptr stack_buffer_size) {
38   static u64 unique_id;
39   unique_id_ = unique_id++;
40   if (auto sz = flags()->heap_history_size)
41     heap_allocations_ = HeapAllocationsRingBuffer::New(sz);
42 
43   HwasanTSDThreadInit();  // Only needed with interceptors.
44   uptr *ThreadLong = GetCurrentThreadLongPtr();
45   // The following implicitly sets (this) as the current thread.
46   stack_allocations_ = new (ThreadLong)
47       StackAllocationsRingBuffer((void *)stack_buffer_start, stack_buffer_size);
48   // Check that it worked.
49   CHECK_EQ(GetCurrentThread(), this);
50 
51   // ScopedTaggingDisable needs GetCurrentThread to be set up.
52   ScopedTaggingDisabler disabler;
53 
54   uptr tls_size;
55   uptr stack_size;
56   GetThreadStackAndTls(IsMainThread(), &stack_bottom_, &stack_size, &tls_begin_,
57                        &tls_size);
58   stack_top_ = stack_bottom_ + stack_size;
59   tls_end_ = tls_begin_ + tls_size;
60 
61   if (stack_bottom_) {
62     int local;
63     CHECK(AddrIsInStack((uptr)&local));
64     CHECK(MemIsApp(stack_bottom_));
65     CHECK(MemIsApp(stack_top_ - 1));
66   }
67 
68   if (flags()->verbose_threads) {
69     if (IsMainThread()) {
70       Printf("sizeof(Thread): %zd sizeof(HeapRB): %zd sizeof(StackRB): %zd\n",
71              sizeof(Thread), heap_allocations_->SizeInBytes(),
72              stack_allocations_->size() * sizeof(uptr));
73     }
74     Print("Creating  : ");
75   }
76 }
77 
78 void Thread::ClearShadowForThreadStackAndTLS() {
79   if (stack_top_ != stack_bottom_)
80     TagMemory(stack_bottom_, stack_top_ - stack_bottom_, 0);
81   if (tls_begin_ != tls_end_)
82     TagMemory(tls_begin_, tls_end_ - tls_begin_, 0);
83 }
84 
85 void Thread::Destroy() {
86   if (flags()->verbose_threads)
87     Print("Destroying: ");
88   AllocatorSwallowThreadLocalCache(allocator_cache());
89   ClearShadowForThreadStackAndTLS();
90   if (heap_allocations_)
91     heap_allocations_->Delete();
92   DTLS_Destroy();
93   // Unregister this as the current thread.
94   // Instrumented code can not run on this thread from this point onwards, but
95   // malloc/free can still be served. Glibc may call free() very late, after all
96   // TSD destructors are done.
97   CHECK_EQ(GetCurrentThread(), this);
98   *GetCurrentThreadLongPtr() = 0;
99 }
100 
101 void Thread::Print(const char *Prefix) {
102   Printf("%sT%zd %p stack: [%p,%p) sz: %zd tls: [%p,%p)\n", Prefix,
103          unique_id_, this, stack_bottom(), stack_top(),
104          stack_top() - stack_bottom(),
105          tls_begin(), tls_end());
106 }
107 
108 static u32 xorshift(u32 state) {
109   state ^= state << 13;
110   state ^= state >> 17;
111   state ^= state << 5;
112   return state;
113 }
114 
115 // Generate a (pseudo-)random non-zero tag.
116 tag_t Thread::GenerateRandomTag() {
117   if (tagging_disabled_) return 0;
118   tag_t tag;
119   do {
120     if (flags()->random_tags) {
121       if (!random_buffer_)
122         random_buffer_ = random_state_ = xorshift(random_state_);
123       CHECK(random_buffer_);
124       tag = random_buffer_ & 0xFF;
125       random_buffer_ >>= 8;
126     } else {
127       tag = random_state_ = (random_state_ + 1) & 0xFF;
128     }
129   } while (!tag);
130   return tag;
131 }
132 
133 } // namespace __hwasan
134