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
8 namespace __dfsan {
9
Create(thread_callback_t start_routine,void * arg,bool track_origins)10 DFsanThread *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
SetThreadStackAndTls()23 void 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
ClearShadowForThreadStackAndTLS()35 void 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
Init()46 void DFsanThread::Init() {
47 SetThreadStackAndTls();
48 ClearShadowForThreadStackAndTLS();
49 }
50
TSDDtor(void * tsd)51 void DFsanThread::TSDDtor(void *tsd) {
52 DFsanThread *t = (DFsanThread *)tsd;
53 t->Destroy();
54 }
55
Destroy()56 void 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
ThreadStart()67 thread_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
GetStackBounds() const86 DFsanThread::StackBounds DFsanThread::GetStackBounds() const {
87 return {stack_.bottom, stack_.top};
88 }
89
stack_top()90 uptr DFsanThread::stack_top() { return GetStackBounds().top; }
91
stack_bottom()92 uptr DFsanThread::stack_bottom() { return GetStackBounds().bottom; }
93
AddrIsInStack(uptr addr)94 bool DFsanThread::AddrIsInStack(uptr addr) {
95 const auto bounds = GetStackBounds();
96 return addr >= bounds.bottom && addr < bounds.top;
97 }
98
99 static pthread_key_t tsd_key;
100 static bool tsd_key_inited = false;
101
DFsanTSDInit(void (* destructor)(void * tsd))102 void 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
108 static THREADLOCAL DFsanThread *dfsan_current_thread;
109
GetCurrentThread()110 DFsanThread *GetCurrentThread() { return dfsan_current_thread; }
111
SetCurrentThread(DFsanThread * t)112 void 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
DFsanTSDDtor(void * tsd)121 void 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