1//=-- ubsan_signals_standalone.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// Installs signal handlers and related interceptors for UBSan standalone.
10//
11//===----------------------------------------------------------------------===//
12
13#include "ubsan_platform.h"
14#include "sanitizer_common/sanitizer_platform.h"
15#if CAN_SANITIZE_UB
16#include "interception/interception.h"
17#include "sanitizer_common/sanitizer_stacktrace.h"
18#include "ubsan_diag.h"
19#include "ubsan_init.h"
20
21// Interception of signals breaks too many things on Android.
22// * It requires that ubsan is the first dependency of the main executable for
23// the interceptors to work correctly. This complicates deployment, as it
24// prevents us from enabling ubsan on random platform modules independently.
25// * For this to work with ART VM, ubsan signal handler has to be set after the
26// debuggerd handler, but before the ART handler.
27// * Interceptors don't work at all when ubsan runtime is loaded late, ex. when
28// it is part of an APK that does not use wrap.sh method.
29#if SANITIZER_FUCHSIA || SANITIZER_ANDROID
30
31namespace __ubsan {
32void InitializeDeadlySignals() {}
33}
34
35#else
36
37namespace __ubsan {
38void InitializeDeadlySignals();
39} // namespace __ubsan
40
41#define COMMON_INTERCEPT_FUNCTION(name) INTERCEPT_FUNCTION(name)
42#define SIGNAL_INTERCEPTOR_ENTER() __ubsan::InitializeDeadlySignals()
43#include "sanitizer_common/sanitizer_signal_interceptors.inc"
44
45// TODO(yln): Temporary workaround. Will be removed.
46void ubsan_GetStackTrace(BufferedStackTrace *stack, uptr max_depth,
47 uptr pc, uptr bp, void *context, bool fast);
48
49namespace __ubsan {
50
51static void OnStackUnwind(const SignalContext &sig, const void *,
52 BufferedStackTrace *stack) {
53 ubsan_GetStackTrace(stack, max_depth: kStackTraceMax,
54 pc: StackTrace::GetNextInstructionPc(pc: sig.pc), bp: sig.bp,
55 context: sig.context, fast: common_flags()->fast_unwind_on_fatal);
56}
57
58static void UBsanOnDeadlySignal(int signo, void *siginfo, void *context) {
59 HandleDeadlySignal(siginfo, context, tid: GetTid(), unwind: &OnStackUnwind, unwind_context: nullptr);
60}
61
62static bool is_initialized = false;
63
64void InitializeDeadlySignals() {
65 if (is_initialized)
66 return;
67 is_initialized = true;
68 InitializeSignalInterceptors();
69#if SANITIZER_INTERCEPT_SIGNAL_AND_SIGACTION
70 // REAL(sigaction_symname) is nullptr in a static link. Bail out.
71 if (!REAL(sigaction_symname))
72 return;
73#endif
74 InstallDeadlySignalHandlers(handler: &UBsanOnDeadlySignal);
75}
76
77} // namespace __ubsan
78
79#endif
80
81#endif // CAN_SANITIZE_UB
82