forked from OSchip/llvm-project
83 lines
3.0 KiB
Plaintext
83 lines
3.0 KiB
Plaintext
This directory contains two utilities for fuzzing Clang: clang-fuzzer and
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clang-proto-fuzzer. Both use libFuzzer to generate inputs to clang via
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coverage-guided mutation.
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The two utilities differ, however, in how they structure inputs to Clang.
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clang-fuzzer makes no attempt to generate valid C++ programs and is therefore
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primarily useful for stressing the surface layers of Clang (i.e. lexer, parser).
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clang-proto-fuzzer uses a protobuf class to describe a subset of the C++
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language and then uses libprotobuf-mutator to mutate instantiations of that
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class, producing valid C++ programs in the process. As a result,
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clang-proto-fuzzer is better at stressing deeper layers of Clang and LLVM.
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===================================
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Building clang-fuzzer
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===================================
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Within your LLVM build directory, run CMake with the following variable
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definitions:
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- CMAKE_C_COMPILER=clang
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- CMAKE_CXX_COMPILER=clang++
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- LLVM_USE_SANITIZE_COVERAGE=YES
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- LLVM_USE_SANITIZER=Address
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Then build the clang-fuzzer target.
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Example:
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cd $LLVM_SOURCE_DIR
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mkdir build && cd build
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cmake .. -GNinja -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ \
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-DLLVM_USE_SANITIZE_COVERAGE=YES -DLLVM_USE_SANITIZER=Address
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ninja clang-fuzzer
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======================
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Running clang-fuzzer
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======================
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bin/clang-fuzzer CORPUS_DIR
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=======================================================
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Building clang-proto-fuzzer (Linux-only instructions)
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=======================================================
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Install the necessary dependencies:
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- binutils // needed for libprotobuf-mutator
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- liblzma-dev // needed for libprotobuf-mutator
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- libz-dev // needed for libprotobuf-mutator
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- docbook2x // needed for libprotobuf-mutator
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- Recent version of protobuf [3.3.0 is known to work]
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Within your LLVM build directory, run CMake with the following variable
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definitions:
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- CMAKE_C_COMPILER=clang
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- CMAKE_CXX_COMPILER=clang++
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- LLVM_USE_SANITIZE_COVERAGE=YES
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- LLVM_USE_SANITIZER=Address
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- CLANG_ENABLE_PROTO_FUZZER=ON
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Then build the clang-proto-fuzzer and clang-proto-to-cxx targets. Optionally,
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you may also build clang-fuzzer with this setup.
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Example:
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cd $LLVM_SOURCE_DIR
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mkdir build && cd build
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cmake .. -GNinja -DCMAKE_C_COMPILER=clang -DCMAKE_CXX_COMPILER=clang++ \
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-DLLVM_USE_SANITIZE_COVERAGE=YES -DLLVM_USE_SANITIZER=Address \
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-DCLANG_ENABLE_PROTO_FUZZER=ON
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ninja clang-proto-fuzzer clang-proto-to-cxx
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This directory also contains a Dockerfile which sets up all required
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dependencies and builds the fuzzers.
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============================
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Running clang-proto-fuzzer
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============================
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bin/clang-proto-fuzzer CORPUS_DIR
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Arguments can be specified after -ignore_remaining_args=1 to modify the compiler
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invocation. For example, the following command line will fuzz LLVM with a
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custom optimization level and target triple:
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bin/clang-proto-fuzzer CORPUS_DIR -ignore_remaining_args=1 -O3 -triple \
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arm64apple-ios9
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To translate a clang-proto-fuzzer corpus output to C++:
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bin/clang-proto-to-cxx CORPUS_OUTPUT_FILE
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