libsanitizer/asan/asan_posix.cpp

   1 //===-- asan_posix.cpp ----------------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file is a part of AddressSanitizer, an address sanity checker.
  10 //
  11 // Posix-specific details.
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "sanitizer_common/sanitizer_platform.h"
  15 #if SANITIZER_POSIX
  16
  17 #  include <pthread.h>
  18 #  include <signal.h>
  19 #  include <stdlib.h>
  20 #  include <sys/resource.h>
  21 #  include <sys/time.h>
  22 #  include <unistd.h>
  23
  24 #  include "asan_interceptors.h"
  25 #  include "asan_internal.h"
  26 #  include "asan_mapping.h"
  27 #  include "asan_poisoning.h"
  28 #  include "asan_report.h"
  29 #  include "asan_stack.h"
  30 #  include "lsan/lsan_common.h"
  31 #  include "sanitizer_common/sanitizer_libc.h"
  32 #  include "sanitizer_common/sanitizer_posix.h"
  33 #  include "sanitizer_common/sanitizer_procmaps.h"
  34
  35 namespace __asan {
  36
  37 void AsanOnDeadlySignal(int signo, void *siginfo, void *context) {
  38   StartReportDeadlySignal();
  39   SignalContext sig(siginfo, context);
  40   ReportDeadlySignal(sig);
  41 }
  42
  43 bool PlatformUnpoisonStacks() {
  44   stack_t signal_stack;
  45   CHECK_EQ(0, sigaltstack(nullptr, &signal_stack));
  46   uptr sigalt_bottom = (uptr)signal_stack.ss_sp;
  47   uptr sigalt_top = (uptr)((char *)signal_stack.ss_sp + signal_stack.ss_size);
  48   // If we're executing on the signal alternate stack AND the Linux flag
  49   // SS_AUTODISARM was used, then we cannot get the signal alternate stack
  50   // bounds from sigaltstack -- sigaltstack's output looks just as if no
  51   // alternate stack has ever been set up.
  52   // We're always unpoisoning the signal alternate stack to support jumping
  53   // between the default stack and signal alternate stack.
  54   if (signal_stack.ss_flags != SS_DISABLE)
  55     UnpoisonStack(sigalt_bottom, sigalt_top, "sigalt");
  56
  57   if (signal_stack.ss_flags != SS_ONSTACK)
  58     return false;
  59
  60   // Since we're on the signal alternate stack, we cannot find the DEFAULT
  61   // stack bottom using a local variable.
  62   uptr stack_begin, stack_end, tls_begin, tls_end;
  63   GetThreadStackAndTls(/*main=*/false, &stack_begin, &stack_end, &tls_begin,
  64                        &tls_end);
  65   UnpoisonStack(stack_begin, stack_end, "default");
  66   return true;
  67 }
  68
  69 // ---------------------- TSD ---------------- {{{1
  70
  71 #if SANITIZER_NETBSD && !ASAN_DYNAMIC
  72 // Thread Static Data cannot be used in early static ASan init on NetBSD.
  73 // Reuse the Asan TSD API for compatibility with existing code
  74 // with an alternative implementation.
  75
  76 static void (*tsd_destructor)(void *tsd) = nullptr;
  77
  78 struct tsd_key {
  79   tsd_key() : key(nullptr) {}
  80   ~tsd_key() {
  81     CHECK(tsd_destructor);
  82     if (key)
  83       (*tsd_destructor)(key);
  84   }
  85   void *key;
  86 };
  87
  88 static thread_local struct tsd_key key;
  89
  90 void AsanTSDInit(void (*destructor)(void *tsd)) {
  91   CHECK(!tsd_destructor);
  92   tsd_destructor = destructor;
  93 }
  94
  95 void *AsanTSDGet() {
  96   CHECK(tsd_destructor);
  97   return key.key;
  98 }
  99
 100 void AsanTSDSet(void *tsd) {
 101   CHECK(tsd_destructor);
 102   CHECK(tsd);
 103   CHECK(!key.key);
 104   key.key = tsd;
 105 }
 106
 107 void PlatformTSDDtor(void *tsd) {
 108   CHECK(tsd_destructor);
 109   CHECK_EQ(key.key, tsd);
 110   key.key = nullptr;
 111   // Make sure that signal handler can not see a stale current thread pointer.
 112   atomic_signal_fence(memory_order_seq_cst);
 113   AsanThread::TSDDtor(tsd);
 114 }
 115 #else
 116 static pthread_key_t tsd_key;
 117 static bool tsd_key_inited = false;
 118 void AsanTSDInit(void (*destructor)(void *tsd)) {
 119   CHECK(!tsd_key_inited);
 120   tsd_key_inited = true;
 121   CHECK_EQ(0, pthread_key_create(&tsd_key, destructor));
 122 }
 123
 124 void *AsanTSDGet() {
 125   CHECK(tsd_key_inited);
 126   return pthread_getspecific(tsd_key);
 127 }
 128
 129 void AsanTSDSet(void *tsd) {
 130   CHECK(tsd_key_inited);
 131   pthread_setspecific(tsd_key, tsd);
 132 }
 133
 134 void PlatformTSDDtor(void *tsd) {
 135   AsanThreadContext *context = (AsanThreadContext *)tsd;
 136   if (context->destructor_iterations > 1) {
 137     context->destructor_iterations--;
 138     CHECK_EQ(0, pthread_setspecific(tsd_key, tsd));
 139     return;
 140   }
 141 #    if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD || \
 142         SANITIZER_SOLARIS
 143   // After this point it's unsafe to execute signal handlers which may be
 144   // instrumented. It's probably not just a Linux issue.
 145   BlockSignals();
 146 #    endif
 147   AsanThread::TSDDtor(tsd);
 148 }
 149 #  endif
 150
 151 static void BeforeFork() {
 152   VReport(2, "BeforeFork tid: %llu\n", GetTid());
 153   if (CAN_SANITIZE_LEAKS) {
 154     __lsan::LockGlobal();
 155   }
 156   // `_lsan` functions defined regardless of `CAN_SANITIZE_LEAKS` and lock the
 157   // stuff we need.
 158   __lsan::LockThreads();
 159   __lsan::LockAllocator();
 160   StackDepotLockBeforeFork();
 161 }
 162
 163 static void AfterFork(bool fork_child) {
 164   StackDepotUnlockAfterFork(fork_child);
 165   // `_lsan` functions defined regardless of `CAN_SANITIZE_LEAKS` and unlock
 166   // the stuff we need.
 167   __lsan::UnlockAllocator();
 168   __lsan::UnlockThreads();
 169   if (CAN_SANITIZE_LEAKS) {
 170     __lsan::UnlockGlobal();
 171   }
 172   VReport(2, "AfterFork tid: %llu\n", GetTid());
 173 }
 174
 175 void InstallAtForkHandler() {
 176 #  if SANITIZER_SOLARIS || SANITIZER_NETBSD || SANITIZER_APPLE || \
 177       (SANITIZER_LINUX && SANITIZER_SPARC)
 178   // While other Linux targets use clone in internal_fork which doesn't
 179   // trigger pthread_atfork handlers, Linux/sparc64 uses __fork, causing a
 180   // hang.
 181   return;  // FIXME: Implement FutexWait.
 182 #  endif
 183   pthread_atfork(
 184       &BeforeFork, []() { AfterFork(/* fork_child= */ false); },
 185       []() { AfterFork(/* fork_child= */ true); });
 186 }
 187
 188 void InstallAtExitCheckLeaks() {
 189   if (CAN_SANITIZE_LEAKS) {
 190     if (common_flags()->detect_leaks && common_flags()->leak_check_at_exit) {
 191       if (flags()->halt_on_error)
 192         Atexit(__lsan::DoLeakCheck);
 193       else
 194         Atexit(__lsan::DoRecoverableLeakCheckVoid);
 195     }
 196   }
 197 }
 198
 199 }  // namespace __asan
 200
 201 #endif  // SANITIZER_POSIX