1#include "dfsan_thread.h"
2
3#include <pthread.h>
4
5#include "dfsan.h"
6#include "sanitizer_common/sanitizer_tls_get_addr.h"
7
8namespace __dfsan {
9
10DFsanThread *DFsanThread::Create(thread_callback_t start_routine, void *arg,
11                                 bool track_origins) {
12  uptr PageSize = GetPageSizeCached();
13  uptr size = RoundUpTo(sizeof(DFsanThread), PageSize);
14  DFsanThread *thread = (DFsanThread *)MmapOrDie(size, __func__);
15  thread->start_routine_ = start_routine;
16  thread->arg_ = arg;
17  thread->track_origins_ = track_origins;
18  thread->destructor_iterations_ = GetPthreadDestructorIterations();
19
20  return thread;
21}
22
23void DFsanThread::SetThreadStackAndTls() {
24  uptr tls_size = 0;
25  uptr stack_size = 0;
26  GetThreadStackAndTls(IsMainThread(), &stack_.bottom, &stack_size, &tls_begin_,
27                       &tls_size);
28  stack_.top = stack_.bottom + stack_size;
29  tls_end_ = tls_begin_ + tls_size;
30
31  int local;
32  CHECK(AddrIsInStack((uptr)&local));
33}
34
35void DFsanThread::ClearShadowForThreadStackAndTLS() {
36  dfsan_set_label(0, (void *)stack_.bottom, stack_.top - stack_.bottom);
37  if (tls_begin_ != tls_end_)
38    dfsan_set_label(0, (void *)tls_begin_, tls_end_ - tls_begin_);
39  DTLS *dtls = DTLS_Get();
40  CHECK_NE(dtls, 0);
41  ForEachDVT(dtls, [](const DTLS::DTV &dtv, int id) {
42    dfsan_set_label(0, (void *)(dtv.beg), dtv.size);
43  });
44}
45
46void DFsanThread::Init() {
47  SetThreadStackAndTls();
48  ClearShadowForThreadStackAndTLS();
49}
50
51void DFsanThread::TSDDtor(void *tsd) {
52  DFsanThread *t = (DFsanThread *)tsd;
53  t->Destroy();
54}
55
56void DFsanThread::Destroy() {
57  malloc_storage().CommitBack();
58  // We also clear the shadow on thread destruction because
59  // some code may still be executing in later TSD destructors
60  // and we don't want it to have any poisoned stack.
61  ClearShadowForThreadStackAndTLS();
62  uptr size = RoundUpTo(sizeof(DFsanThread), GetPageSizeCached());
63  UnmapOrDie(this, size);
64  DTLS_Destroy();
65}
66
67thread_return_t DFsanThread::ThreadStart() {
68  if (!start_routine_) {
69    // start_routine_ == 0 if we're on the main thread or on one of the
70    // OS X libdispatch worker threads. But nobody is supposed to call
71    // ThreadStart() for the worker threads.
72    return 0;
73  }
74
75  // The only argument is void* arg.
76  //
77  // We have never supported propagating the pointer arg as tainted,
78  // __dfsw_pthread_create/__dfso_pthread_create ignore the taint label.
79  // Note that the bytes pointed-to (probably the much more common case)
80  // can still have taint labels attached to them.
81  dfsan_clear_thread_local_state();
82
83  return start_routine_(arg_);
84}
85
86DFsanThread::StackBounds DFsanThread::GetStackBounds() const {
87  return {stack_.bottom, stack_.top};
88}
89
90uptr DFsanThread::stack_top() { return GetStackBounds().top; }
91
92uptr DFsanThread::stack_bottom() { return GetStackBounds().bottom; }
93
94bool DFsanThread::AddrIsInStack(uptr addr) {
95  const auto bounds = GetStackBounds();
96  return addr >= bounds.bottom && addr < bounds.top;
97}
98
99static pthread_key_t tsd_key;
100static bool tsd_key_inited = false;
101
102void DFsanTSDInit(void (*destructor)(void *tsd)) {
103  CHECK(!tsd_key_inited);
104  tsd_key_inited = true;
105  CHECK_EQ(0, pthread_key_create(&tsd_key, destructor));
106}
107
108static THREADLOCAL DFsanThread *dfsan_current_thread;
109
110DFsanThread *GetCurrentThread() { return dfsan_current_thread; }
111
112void SetCurrentThread(DFsanThread *t) {
113  // Make sure we do not reset the current DFsanThread.
114  CHECK_EQ(0, dfsan_current_thread);
115  dfsan_current_thread = t;
116  // Make sure that DFsanTSDDtor gets called at the end.
117  CHECK(tsd_key_inited);
118  pthread_setspecific(tsd_key, t);
119}
120
121void DFsanTSDDtor(void *tsd) {
122  DFsanThread *t = (DFsanThread *)tsd;
123  if (t->destructor_iterations_ > 1) {
124    t->destructor_iterations_--;
125    CHECK_EQ(0, pthread_setspecific(tsd_key, tsd));
126    return;
127  }
128  dfsan_current_thread = nullptr;
129  // Make sure that signal handler can not see a stale current thread pointer.
130  atomic_signal_fence(memory_order_seq_cst);
131  DFsanThread::TSDDtor(tsd);
132}
133
134}  // namespace __dfsan
135