From: Philip Pronin <philipp@fb.com>
Date: Fri, 11 Dec 2015 00:15:37 +0000 (-0800)
Subject: setup signal handler with SA_ONSTACK
X-Git-Tag: deprecate-dynamic-initializer~190
X-Git-Url: http://plrg.eecs.uci.edu/git/?a=commitdiff_plain;h=dee3186eca21211a0e031f5489b32326a3b9ddd2;p=folly.git

setup signal handler with SA_ONSTACK

Summary:
By default signal handlers are run on the signaled thread's stack.
In case of stack overflow running the `SIGSEGV` signal handler on
the same stack leads to another `SIGSEGV` and crashes the program
Use `SA_ONSTACK`, so alternate stack is used (only if configured via
`sigaltstack`).

Reviewed By: luciang

Differential Revision: D2747021

fb-gh-sync-id: 48388acd6147e2919412ec32acfca1ca76f22a16
---

diff --git a/folly/experimental/symbolizer/SignalHandler.cpp b/folly/experimental/symbolizer/SignalHandler.cpp
index 5ec13bdf..86434f8b 100644
--- a/folly/experimental/symbolizer/SignalHandler.cpp
+++ b/folly/experimental/symbolizer/SignalHandler.cpp
@@ -322,7 +322,12 @@ void installFatalSignalHandler() {
   struct sigaction sa;
   memset(&sa, 0, sizeof(sa));
   sigemptyset(&sa.sa_mask);
-  sa.sa_flags |= SA_SIGINFO;
+  // By default signal handlers are run on the signaled thread's stack.
+  // In case of stack overflow running the SIGSEGV signal handler on
+  // the same stack leads to another SIGSEGV and crashes the program.
+  // Use SA_ONSTACK, so alternate stack is used (only if configured via
+  // sigaltstack).
+  sa.sa_flags |= SA_SIGINFO | SA_ONSTACK;
   sa.sa_sigaction = &signalHandler;
 
   for (auto p = kFatalSignals; p->name; ++p) {