2.1 KiB
Fuzzers
These are fuzzers designed for use with libFuzzer or afl. They can
be used to run on Google's OSS-Fuzz (https://github.com/google/oss-fuzz/).
The convention used here is that the initial values for each parser fuzzer are taken from the $NAME.in directory.
Crash reproducers from OSS-Fuzz are put into $NAME.repro directory for regression testing with top dir 'make check' or 'make check-valgrind'.
The ./configure runs below are for libidn2. To test libicu replace 'libidn2' with 'libicu', to test with libidn replace 'libidn2' by 'libidn'.
Running a fuzzer using clang
Use the following commands on top dir:
export CC=clang-5.0
export CXX=clang++-5.0
export CFLAGS="-O1 -fno-omit-frame-pointer -gline-tables-only -DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION -fsanitize=address -fsanitize-address-use-after-scope -fsanitize-coverage=trace-pc-guard,trace-cmp"
export CXXFLAGS="-O1 -fno-omit-frame-pointer -gline-tables-only -DFUZZING_BUILD_MODE_UNSAFE_FOR_PRODUCTION -fsanitize=address -fsanitize-address-use-after-scope -fsanitize-coverage=trace-pc-guard,trace-cmp -stdlib=libc++"
./configure --enable-static --disable-gtk-doc --enable-runtime=libidn2 --enable-builtin=libidn2
make clean
make -j$(nproc)
cd fuzz
# build and run libpsl_fuzzer
./run-clang.sh libpsl_fuzzer
Running a fuzzer using AFL
Use the following commands on top dir:
$ CC=afl-clang-fast ./configure --disable-gtk-doc --enable-runtime=libidn2 --enable-builtin=libidn2
$ make -j$(nproc) clean all
$ cd fuzz
$ ./run-afl.sh libpsl_fuzzer
Fuzz code coverage using the corpus directories *.in/
Code coverage reports currently work best with gcc+lcov+genhtml.
In the top directory:
CC=gcc CFLAGS="-O0 -g" ./configure --disable-gtk-doc --enable-runtime=libidn2 --enable-builtin=libidn2
make fuzz-coverage
xdg-open lcov/index.html
Each fuzzer target has it's own functions to cover, e.g.
libpsl_fuzzer covers psl_is_public_suffix.
To work on corpora for better coverage, cd fuzz and use e.g.
./view-coverage.sh libpsl_fuzzer.
Enhancing the testsuite for issues found
Each reproducer file should be dropped into the appropriate *.repro/ directory.