asan_posix.cc revision 4c49666e611f06241bb8462cea7674d877241492 
1//===-- asan_linux.cc -----------------------------------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file is a part of AddressSanitizer, an address sanity checker.
11//
12// Posix-specific details.
13//===----------------------------------------------------------------------===//
14#if defined(__linux__) || defined(__APPLE__)
15
16#include "asan_internal.h"
17#include "asan_interceptors.h"
18#include "asan_mapping.h"
19#include "asan_stack.h"
20#include "asan_thread_registry.h"
21#include "sanitizer_common/sanitizer_libc.h"
22#include "sanitizer_common/sanitizer_procmaps.h"
23
24#include <pthread.h>
25#include <signal.h>
26#include <stdlib.h>
27#include <sys/time.h>
28#include <sys/resource.h>
29#include <unistd.h>
30
31static const uptr kAltStackSize = SIGSTKSZ * 4;  // SIGSTKSZ is not enough.
32
33namespace __asan {
34
35static inline bool IntervalsAreSeparate(uptr start1, uptr end1,
36                                        uptr start2, uptr end2) {
37  CHECK(start1 <= end1);
38  CHECK(start2 <= end2);
39  return (end1 < start2) || (end2 < start1);
40}
41
42// FIXME: this is thread-unsafe, but should not cause problems most of the time.
43// When the shadow is mapped only a single thread usually exists (plus maybe
44// several worker threads on Mac, which aren't expected to map big chunks of
45// memory).
46bool AsanShadowRangeIsAvailable() {
47  ProcessMaps procmaps;
48  uptr start, end;
49  uptr shadow_start = kLowShadowBeg;
50  if (kLowShadowBeg > 0) shadow_start -= kMmapGranularity;
51  uptr shadow_end = kHighShadowEnd;
52  while (procmaps.Next(&start, &end,
53                       /*offset*/0, /*filename*/0, /*filename_size*/0)) {
54    if (!IntervalsAreSeparate(start, end, shadow_start, shadow_end))
55      return false;
56  }
57  return true;
58}
59
60static void MaybeInstallSigaction(int signum,
61                                  void (*handler)(int, siginfo_t *, void *)) {
62  if (!AsanInterceptsSignal(signum))
63    return;
64  struct sigaction sigact;
65  REAL(memset)(&sigact, 0, sizeof(sigact));
66  sigact.sa_sigaction = handler;
67  sigact.sa_flags = SA_SIGINFO;
68  if (FLAG_use_sigaltstack) sigact.sa_flags |= SA_ONSTACK;
69  CHECK(0 == REAL(sigaction)(signum, &sigact, 0));
70  if (FLAG_v >= 1) {
71    Report("Installed the sigaction for signal %d\n", signum);
72  }
73}
74
75static void     ASAN_OnSIGSEGV(int, siginfo_t *siginfo, void *context) {
76  uptr addr = (uptr)siginfo->si_addr;
77  // Write the first message using the bullet-proof write.
78  if (13 != internal_write(2, "ASAN:SIGSEGV\n", 13)) Die();
79  uptr pc, sp, bp;
80  GetPcSpBp(context, &pc, &sp, &bp);
81  AsanReport("ERROR: AddressSanitizer crashed on unknown address %p"
82             " (pc %p sp %p bp %p T%d)\n",
83             (void*)addr, (void*)pc, (void*)sp, (void*)bp,
84             asanThreadRegistry().GetCurrentTidOrInvalid());
85  AsanPrintf("AddressSanitizer can not provide additional info. ABORTING\n");
86  GET_STACK_TRACE_WITH_PC_AND_BP(kStackTraceMax, pc, bp);
87  stack.PrintStack();
88  ShowStatsAndAbort();
89}
90
91void SetAlternateSignalStack() {
92  stack_t altstack, oldstack;
93  CHECK(0 == sigaltstack(0, &oldstack));
94  // If the alternate stack is already in place, do nothing.
95  if ((oldstack.ss_flags & SS_DISABLE) == 0) return;
96  // TODO(glider): the mapped stack should have the MAP_STACK flag in the
97  // future. It is not required by man 2 sigaltstack now (they're using
98  // malloc()).
99  void* base = MmapOrDie(kAltStackSize, __FUNCTION__);
100  altstack.ss_sp = base;
101  altstack.ss_flags = 0;
102  altstack.ss_size = kAltStackSize;
103  CHECK(0 == sigaltstack(&altstack, 0));
104  if (FLAG_v > 0) {
105    Report("Alternative stack for T%d set: [%p,%p)\n",
106           asanThreadRegistry().GetCurrentTidOrInvalid(),
107           altstack.ss_sp, (char*)altstack.ss_sp + altstack.ss_size);
108  }
109}
110
111void UnsetAlternateSignalStack() {
112  stack_t altstack, oldstack;
113  altstack.ss_sp = 0;
114  altstack.ss_flags = SS_DISABLE;
115  altstack.ss_size = 0;
116  CHECK(0 == sigaltstack(&altstack, &oldstack));
117  UnmapOrDie(oldstack.ss_sp, oldstack.ss_size);
118}
119
120void InstallSignalHandlers() {
121  // Set the alternate signal stack for the main thread.
122  // This will cause SetAlternateSignalStack to be called twice, but the stack
123  // will be actually set only once.
124  if (FLAG_use_sigaltstack) SetAlternateSignalStack();
125  MaybeInstallSigaction(SIGSEGV, ASAN_OnSIGSEGV);
126  MaybeInstallSigaction(SIGBUS, ASAN_OnSIGSEGV);
127}
128
129// ---------------------- TSD ---------------- {{{1
130
131static pthread_key_t tsd_key;
132static bool tsd_key_inited = false;
133void AsanTSDInit(void (*destructor)(void *tsd)) {
134  CHECK(!tsd_key_inited);
135  tsd_key_inited = true;
136  CHECK(0 == pthread_key_create(&tsd_key, destructor));
137}
138
139void *AsanTSDGet() {
140  CHECK(tsd_key_inited);
141  return pthread_getspecific(tsd_key);
142}
143
144void AsanTSDSet(void *tsd) {
145  CHECK(tsd_key_inited);
146  pthread_setspecific(tsd_key, tsd);
147}
148
149}  // namespace __asan
150
151#endif  // __linux__ || __APPLE_
152