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