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
35namespace __asan {
36
37void AsanOnDeadlySignal(int signo, void *siginfo, void *context) {
38 StartReportDeadlySignal();
39 SignalContext sig(siginfo, context);
40 ReportDeadlySignal(sig);
41}
42
43bool 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(bottom: sigalt_bottom, top: sigalt_top, type: "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 default_bottom, tls_addr, tls_size, stack_size;
63 GetThreadStackAndTls(/*main=*/false, stk_addr: &default_bottom, stk_size: &stack_size, tls_addr: &tls_addr,
64 tls_size: &tls_size);
65 UnpoisonStack(bottom: default_bottom, top: default_bottom + stack_size, type: "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
76static void (*tsd_destructor)(void *tsd) = nullptr;
77
78struct 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
88static thread_local struct tsd_key key;
89
90void AsanTSDInit(void (*destructor)(void *tsd)) {
91 CHECK(!tsd_destructor);
92 tsd_destructor = destructor;
93}
94
95void *AsanTSDGet() {
96 CHECK(tsd_destructor);
97 return key.key;
98}
99
100void AsanTSDSet(void *tsd) {
101 CHECK(tsd_destructor);
102 CHECK(tsd);
103 CHECK(!key.key);
104 key.key = tsd;
105}
106
107void 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
116static pthread_key_t tsd_key;
117static bool tsd_key_inited = false;
118void 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
124void *AsanTSDGet() {
125 CHECK(tsd_key_inited);
126 return pthread_getspecific(key: tsd_key);
127}
128
129void AsanTSDSet(void *tsd) {
130 CHECK(tsd_key_inited);
131 pthread_setspecific(key: tsd_key, pointer: tsd);
132}
133
134void 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
151static void BeforeFork() {
152 if (CAN_SANITIZE_LEAKS) {
153 __lsan::LockGlobal();
154 }
155 // `_lsan` functions defined regardless of `CAN_SANITIZE_LEAKS` and lock the
156 // stuff we need.
157 __lsan::LockThreads();
158 __lsan::LockAllocator();
159 StackDepotLockBeforeFork();
160}
161
162static void AfterFork(bool fork_child) {
163 StackDepotUnlockAfterFork(fork_child);
164 // `_lsan` functions defined regardless of `CAN_SANITIZE_LEAKS` and unlock
165 // the stuff we need.
166 __lsan::UnlockAllocator();
167 __lsan::UnlockThreads();
168 if (CAN_SANITIZE_LEAKS) {
169 __lsan::UnlockGlobal();
170 }
171}
172
173void InstallAtForkHandler() {
174# if SANITIZER_SOLARIS || SANITIZER_NETBSD || SANITIZER_APPLE
175 return; // FIXME: Implement FutexWait.
176# endif
177 pthread_atfork(
178 prepare: &BeforeFork, parent: []() { AfterFork(/* fork_child= */ false); },
179 child: []() { AfterFork(/* fork_child= */ true); });
180}
181
182void InstallAtExitCheckLeaks() {
183 if (CAN_SANITIZE_LEAKS) {
184 if (common_flags()->detect_leaks && common_flags()->leak_check_at_exit) {
185 if (flags()->halt_on_error)
186 Atexit(function: __lsan::DoLeakCheck);
187 else
188 Atexit(function: __lsan::DoRecoverableLeakCheckVoid);
189 }
190 }
191}
192
193} // namespace __asan
194
195#endif // SANITIZER_POSIX
196

source code of compiler-rt/lib/asan/asan_posix.cpp