2f92e9eb6b
In a recent CL I moved the corpus of the wasm fuzzer and of the wasm-asmjs fuzzer to a different directory (wasm_corpus and wasm_asmjs_corpus) so that the corpus is not executed on the try-bots. With this CL I remove the old corpus from the .gitignore file. In addition I removed the hooks for wasm_corpus and wasm_asmjs_corpus from the V8 DEPS file, because in a V8 checkout they are not used anyway. I also added code to the test runner to delete all *.wasm files from the directories test/fuzzer/wasm and test/fuzzer/wasm_asmjs. This code should be removed in a week, but it will help my coworkers to cleanup their V8 checkout. R=bradnelson@chromium.org CC=machenbach@chromium.org Change-Id: I9fdf9d77b71b133f84f7e744763d65fdf127d624 Reviewed-on: https://chromium-review.googlesource.com/505614 Commit-Queue: Andreas Haas <ahaas@chromium.org> Reviewed-by: Michael Achenbach <machenbach@chromium.org> Cr-Commit-Position: refs/heads/master@{#45417} |
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|---|---|---|
| .. | ||
| json | ||
| parser | ||
| regexp | ||
| wasm | ||
| wasm_asmjs | ||
| wasm_call | ||
| wasm_code | ||
| wasm_compile | ||
| wasm_data_section | ||
| wasm_function_sigs_section | ||
| wasm_globals_section | ||
| wasm_imports_section | ||
| wasm_memory_section | ||
| wasm_names_section | ||
| wasm_types_section | ||
| DEPS | ||
| fuzzer-support.cc | ||
| fuzzer-support.h | ||
| fuzzer.cc | ||
| fuzzer.gyp | ||
| fuzzer.isolate | ||
| fuzzer.status | ||
| json.cc | ||
| parser.cc | ||
| README.md | ||
| regexp.cc | ||
| testcfg.py | ||
| wasm_asmjs_corpus.tar.gz.sha1 | ||
| wasm_corpus.tar.gz.sha1 | ||
| wasm-asmjs.cc | ||
| wasm-call.cc | ||
| wasm-code.cc | ||
| wasm-compile.cc | ||
| wasm-data-section.cc | ||
| wasm-function-sigs-section.cc | ||
| wasm-fuzzer-common.cc | ||
| wasm-fuzzer-common.h | ||
| wasm-globals-section.cc | ||
| wasm-imports-section.cc | ||
| wasm-memory-section.cc | ||
| wasm-names-section.cc | ||
| wasm-types-section.cc | ||
| wasm.cc | ||
How to make a libFuzzer fuzzer in V8
This document describes how to make a new libFuzzer fuzzer for V8. A general introduction to libFuzzer can be found here. In short, libFuzzer is an in-process coverage-driven evolutionary fuzzer. libFuzzer serves you with a sequence of byte arrays that you can use to test your code. libFuzzer tries to generate this sequence of byte arrays in a way that maximizes test coverage.
Warning: By itself libFuzzer typically does not generate valid JavaScript code.
Changes to V8
tldr: Do the same as https://codereview.chromium.org/2280623002 to introduce a new fuzzer to V8.
This is a step by step guide on how to make a new fuzzer in V8. In the example
the fuzzer is called foo.
-
Copy one of the existing fuzzer implementations in test/fuzzer/, e.g.
cp wasm.cc foo.cc- Copying an existing fuzzer is a good idea to get all the required setup, e.g. setting up the isolate
-
Create a directory called
fooin test/fuzzer/ which contains at least one file- The file is used by the trybots to check whether the fuzzer actually compiles and runs
-
Copy the build rules of an existing fuzzer in BUILD.gn, e.g. the build rules for the wasm.cc fuzzer are
v8_source_set("wasm_fuzzer")andv8_fuzzer("wasm_fuzzer"). Note that the name has to be the name of the directory created in Step 2 +_fuzzerso that the scripts on the trybots work -
Now you can already compile the fuzzer, e.g. with
ninja -j 1000 -C out/x64.debug/v8_simple_foo_fuzzer- Use this binary to reproduce issues found by cluster fuzz, e.g.
out/x64.debug/v8_simple_foo_fuzzer testcase.foo
- Use this binary to reproduce issues found by cluster fuzz, e.g.
-
Copy the build rules of an existing fuzzer in test/fuzzer/fuzzer.gyp, e.g. the build rules for the wasm.cc fuzzer are
v8_simple_wasm_fuzzerandwasm_fuzzer_lib- This build rule is needed to compile with gyp
-
Copy the binary name and the test directory name in test/fuzzer/fuzzer.isolate
-
Add the fuzzer to the FuzzerTestSuite in test/fuzzer/testcfg.py
- This step is needed to run the fuzzer with the files created in Step 2 on the trybots
-
Commit the changes described above to the V8 repository
Changes to Chromium
tldr: Do the same as https://codereview.chromium.org/2344823002 to add the new fuzzer to cluster fuzz.
-
Copy the build rules of an existing fuzzer in testing/libfuzzer/fuzzers/BUILD.gn, e.g. the build rule for the wasm.cc fuzzer is
v8_wasm_fuzzer. There is no need to set adictionary, or aseed_corpus. See chromium-fuzzing-getting-started for more information. -
Compile the fuzzer in chromium (for different configurations see: https://chromium.googlesource.com/chromium/src/+/master/testing/libfuzzer/reproducing.md):
-
gn gen out/libfuzzer '--args=use_libfuzzer=true is_asan=true is_debug=false enable_nacl=false' -
ninja -j 1000 -C out/libfuzzer/ v8_foo_fuzzer
-
-
Run the fuzzer locally
mkdir /tmp/empty_corpus && out/libfuzzer/v8_foo_fuzzer /tmp/empty_corpus