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 
31 namespace __ubsan {
32 void InitializeDeadlySignals() {}
33 }
34 
35 #else
36 
37 namespace __ubsan {
38 void 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.
46 void ubsan_GetStackTrace(BufferedStackTrace *stack, uptr max_depth,
47                          uptr pc, uptr bp, void *context, bool fast);
48 
49 namespace __ubsan {
50 
51 static void OnStackUnwind(const SignalContext &sig, const void *,
52                           BufferedStackTrace *stack) {
53   ubsan_GetStackTrace(stack, kStackTraceMax,
54                       StackTrace::GetNextInstructionPc(sig.pc), sig.bp,
55                       sig.context, common_flags()->fast_unwind_on_fatal);
56 }
57 
58 static void UBsanOnDeadlySignal(int signo, void *siginfo, void *context) {
59   HandleDeadlySignal(siginfo, context, GetTid(), &OnStackUnwind, nullptr);
60 }
61 
62 static bool is_initialized = false;
63 
64 void InitializeDeadlySignals() {
65   if (is_initialized)
66     return;
67   is_initialized = true;
68   InitializeSignalInterceptors();
69   InstallDeadlySignalHandlers(&UBsanOnDeadlySignal);
70 }
71 
72 } // namespace __ubsan
73 
74 #endif
75 
76 #endif // CAN_SANITIZE_UB
77