[ASan] allow deadly signals to be received in signal handlers

(previously ASan would just crash upon the second SEGV)
Other tools do not use this code yet.

llvm-svn: 217137

1 files changed, 3 insertions, 1 deletions

diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cc b/compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cc
index e79563a2f84..b5b24634ffe 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cc
@@ -148,7 +148,9 @@ static void MaybeInstallSigaction(int signum,
   struct sigaction sigact;
   internal_memset(&sigact, 0, sizeof(sigact));
   sigact.sa_sigaction = (sa_sigaction_t)handler;
-  sigact.sa_flags = SA_SIGINFO;
+  // Do not block the signal from being received in that signal's handler.
+  // Clients are responsible for handling this correctly.
+  sigact.sa_flags = SA_SIGINFO | SA_NODEFER;
   if (common_flags()->use_sigaltstack) sigact.sa_flags |= SA_ONSTACK;
   CHECK_EQ(0, internal_sigaction(signum, &sigact, 0));
   VReport(1, "Installed the sigaction for signal %d\n", signum);