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[libFuzzer] always install signal handler with SA_ONSTACK #147422

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[libFuzzer] always install signal handler with SA_ONSTACK #147422

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12 changes: 8 additions & 4 deletions compiler-rt/lib/fuzzer/FuzzerUtilPosix.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -78,10 +78,14 @@ static void SetSigaction(int signum,
}

struct sigaction new_sigact = {};
// Address sanitizer needs SA_ONSTACK (causing the signal handler to run on a
// dedicated stack) in order to be able to detect stack overflows; keep the
// flag if it's set.
new_sigact.sa_flags = SA_SIGINFO | (sigact.sa_flags & SA_ONSTACK);
// SA_ONSTACK is required for certain runtimes that use small stacks, for
// instance the Go runtime.
// See https://github.com/golang/go/issues/49075
// Address sanitizer also wants SA_ONSTACK, and the fuzzer and sanitizer
// often run together.
// SA_ONSTACK is a no-op unless someone also calls sigaltstack. That is left
// up to code that needs it.
new_sigact.sa_flags = SA_SIGINFO | SA_ONSTACK;
new_sigact.sa_sigaction = callback;
if (sigaction(signum, &new_sigact, nullptr)) {
Printf("libFuzzer: sigaction failed with %d\n", errno);
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