From dfc86c0f25126ce3242b317087234c7228418eb2 Mon Sep 17 00:00:00 2001 From: Alexander Bulekov Date: Tue, 13 Jul 2021 11:00:37 -0400 Subject: fuzz: add an instrumentation filter By default, -fsanitize=fuzzer instruments all code with coverage information. However, this means that libfuzzer will track coverage over hundreds of source files that are unrelated to virtual-devices. This means that libfuzzer will optimize inputs for coverage observed in timer code, memory APIs etc. This slows down the fuzzer and stores many inputs that are not relevant to the actual virtual-devices. With this change, clang versions that support the "-fsanitize-coverage-allowlist" will only instrument a subset of the compiled code, that is directly related to virtual-devices. Signed-off-by: Alexander Bulekov Reviewed-by: Darren Kenny --- scripts/oss-fuzz/instrumentation-filter-template | 15 +++++++++++++++ 1 file changed, 15 insertions(+) create mode 100644 scripts/oss-fuzz/instrumentation-filter-template (limited to 'scripts') diff --git a/scripts/oss-fuzz/instrumentation-filter-template b/scripts/oss-fuzz/instrumentation-filter-template new file mode 100644 index 0000000..76d2b61 --- /dev/null +++ b/scripts/oss-fuzz/instrumentation-filter-template @@ -0,0 +1,15 @@ +# Code that we actually want the fuzzer to target +# See: https://clang.llvm.org/docs/SanitizerCoverage.html#disabling-instrumentation-without-source-modification +# +src:*/hw/* +src:*/include/hw/* +src:*/slirp/* +src:*/net/* + +# We don't care about coverage over fuzzer-specific code, however we should +# instrument the fuzzer entry-point so libFuzzer always sees at least some +# coverage - otherwise it will exit after the first input +src:*/tests/qtest/fuzz/fuzz.c + +# Enable instrumentation for all functions in those files +fun:* -- cgit v1.1