[Sanitizers] By default build libFuzzer with frame pointers.

[alekseyshl]

Summary

Lacking frame pointers, sanitized fuzzers collect bogus stack
traces and the set of stack traces grows indefinitely, leading to OOMs.

[eugenis]

lib/fuzzer/CMakeLists.txt

35

COMPILER_RT_LIBFUZZER_OMIT_FRAME_POINTER - why is it needed? We don't have a similar escape hatch for every other compiler option, why start now?

[alekseyshl]

lib/fuzzer/CMakeLists.txt

35

If your fuzz target is going to be built with no sanitizers, why would you need frame pointers? Or you think it's excessive and frame pointers are not a big deal to always have them?

[eugenis]

lib/fuzzer/CMakeLists.txt

35

No one really does that, I hope.
Also, libfuzzer is now part of the toolchain, and people building fuzz targets don't rebuild it.

[alekseyshl]

• Always build libFuzzer with frame pointers

[alekseyshl]

rL315770

lib/fuzzer/CMakeLists.txt

CHECK_CXX_SOURCE_COMPILES("
   static thread_local int blah;
   int main() {
   return 0;
   }
   " HAS_THREAD_LOCAL)
 
 set(LIBFUZZER_CFLAGS ${SANITIZER_COMMON_CFLAGS})
 
+append_list_if(COMPILER_RT_HAS_OMIT_FRAME_POINTER_FLAG -fno-omit-frame-pointer LIBFUZZER_CFLAGS)
+
 if (CMAKE_CXX_FLAGS MATCHES "fsanitize-coverage")
   list(APPEND LIBFUZZER_CFLAGS -fno-sanitize-coverage=trace-pc-guard,edge,trace-cmp,indirect-calls,8bit-counters)
 endif()
 
 if(NOT HAS_THREAD_LOCAL)
   list(APPEND LIBFUZZER_CFLAGS -Dthread_local=__thread)
 endif()