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Workaround Android sigaction bug

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On Android L+, signal and sigaction symbols are provided by libsigchain
that override the system's versions. There is a bug in these functions
where they essentially ignore requests to install SIG_DFL.

Workaround this issue by explicitly performing a syscall to
__NR_rt_sigaction to install SIG_DFL on Android.

BUG=473973

Patch by Chris Hopman <cjhopman@chromium.org>
Review URL: https://breakpad.appspot.com/1804002/


git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1438 4c0a9323-5329-0410-9bdc-e9ce6186880e
This commit is contained in:
mark@chromium.org 2015-04-10 17:57:24 +00:00
parent 48b9a40539
commit cfdf7cf8a9
1 changed files with 21 additions and 3 deletions
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24
src/client/linux/handler/exception_handler.cc
View file

@ -188,6 +188,24 @@ void RestoreAlternateStackLocked() {
stack_installed = false; stack_installed = false;
} }
void InstallDefaultHandler(int sig) {
#if defined(__ANDROID__)
// Android L+ expose signal and sigaction symbols that override the system
// ones. There is a bug in these functions where a request to set the handler
// to SIG_DFL is ignored. In that case, an infinite loop is entered as the
// signal is repeatedly sent to breakpad's signal handler.
// To work around this, directly call the system's sigaction.
struct sigaction sa;
memset(&sa, 0, sizeof(sa));
sigemptyset(&sa.sa_mask);
sa.sa_handler = SIG_DFL;
sa.sa_flags = SA_RESTART;
syscall(__NR_sigaction, sig, &sa, NULL);
#else
signal(sig, SIG_DFL);
#endif
}
// The global exception handler stack. This is needed because there may exist // The global exception handler stack. This is needed because there may exist
// multiple ExceptionHandler instances in a process. Each will have itself // multiple ExceptionHandler instances in a process. Each will have itself
// registered in this stack. // registered in this stack.
@ -283,7 +301,7 @@ void ExceptionHandler::RestoreHandlersLocked() {
for (int i = 0; i < kNumHandledSignals; ++i) { for (int i = 0; i < kNumHandledSignals; ++i) {
if (sigaction(kExceptionSignals[i], &old_handlers[i], NULL) == -1) { if (sigaction(kExceptionSignals[i], &old_handlers[i], NULL) == -1) {
signal(kExceptionSignals[i], SIG_DFL); InstallDefaultHandler(kExceptionSignals[i]);
} }
} }
handlers_installed = false; handlers_installed = false;
@ -323,7 +341,7 @@ void ExceptionHandler::SignalHandler(int sig, siginfo_t* info, void* uc) {
if (sigaction(sig, &cur_handler, NULL) == -1) { if (sigaction(sig, &cur_handler, NULL) == -1) {
// When resetting the handler fails, try to reset the // When resetting the handler fails, try to reset the
// default one to avoid an infinite loop here. // default one to avoid an infinite loop here.
signal(sig, SIG_DFL); InstallDefaultHandler(sig);
} }
pthread_mutex_unlock(&g_handler_stack_mutex_); pthread_mutex_unlock(&g_handler_stack_mutex_);
return; return;
@ -340,7 +358,7 @@ void ExceptionHandler::SignalHandler(int sig, siginfo_t* info, void* uc) {
// previously installed handler. Then, when the signal is retriggered, it will // previously installed handler. Then, when the signal is retriggered, it will
// be delivered to the appropriate handler. // be delivered to the appropriate handler.
if (handled) { if (handled) {
signal(sig, SIG_DFL); InstallDefaultHandler(sig);
} else { } else {
RestoreHandlersLocked(); RestoreHandlersLocked();
} }