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History

Victor Zverovich 2711cb1672 Apply clang format and other minor formatting tweaks		2019-06-30 08:52:15 -07:00
..
.gitignore
build.sh
chrono_duration.cpp
CMakeLists.txt	Apply clang format and other minor formatting tweaks	2019-06-30 08:52:15 -07:00
fuzzer_common.h	Apply clang format and other minor formatting tweaks	2019-06-30 08:52:15 -07:00
main.cpp	Apply clang format and other minor formatting tweaks	2019-06-30 08:52:15 -07:00
named_arg.cpp	Apply clang format and other minor formatting tweaks	2019-06-30 08:52:15 -07:00
one_arg.cpp	Apply clang format and other minor formatting tweaks	2019-06-30 08:52:15 -07:00
README.md	Apply clang format and other minor formatting tweaks	2019-06-30 08:52:15 -07:00
sprintf.cpp
two_args.cpp	Apply clang format and other minor formatting tweaks	2019-06-30 08:52:15 -07:00

README.md

FMT Fuzzer

Fuzzing has revealed several bugs in fmt. It is a part of the continous fuzzing at oss-fuzz.

The source code is modified to make the fuzzing possible without locking up on resource exhaustion:

#ifdef FUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION
if(spec.precision>100000) {
  throw std::runtime_error("fuzz mode - avoiding large precision");
}
#endif

This macro is the defacto standard for making fuzzing practically possible, see the libFuzzer documentation.

Running the fuzzers locally

There is a helper script to build the fuzzers, which has only been tested on Debian and Ubuntu linux so far. There should be no problems fuzzing on Windows (using clang>=8) or on Mac, but the script will probably not work out of the box.

Something along

mkdir build
cd build
export CXX=clang++
export CXXFLAGS="-fsanitize=fuzzer-no-link -DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION= -g"
cmake ..  -DFMT_SAFE_DURATION_CAST=On -DFMT_FUZZ=On -DFMT_FUZZ_LINKMAIN=Off -DFMT_FUZZ_LDFLAGS="-fsanitize=fuzzer"
cmake --build .

should work to build the fuzzers for all platforms which clang supports.

Execute a fuzzer with for instance

cd build
export UBSAN_OPTIONS=halt_on_error=1
mkdir out_chrono
bin/fuzzer_chrono_duration  out_chrono