74794fb937
These instructions were changed from "s8x16" to "i8x16" prefixes in https://github.com/WebAssembly/simd/pull/321. This CL updates all V8 code, including arch-specific code, to match. Bug: v8:10946, v8:10933 Change-Id: I26ef9ad77571f94501d42c1d65f57380fd507f3d Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2432068 Reviewed-by: Zhi An Ng <zhin@chromium.org> Commit-Queue: Adam Klein <adamk@chromium.org> Cr-Commit-Position: refs/heads/master@{#70143} |
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.. | ||
json | ||
multi_return | ||
parser | ||
regexp | ||
regexp_builtins | ||
wasm | ||
wasm_async | ||
wasm_code | ||
wasm_compile | ||
BUILD.gn | ||
DEPS | ||
fuzzer-support.cc | ||
fuzzer-support.h | ||
fuzzer.cc | ||
fuzzer.status | ||
json.cc | ||
multi-return.cc | ||
parser.cc | ||
README.md | ||
regexp-builtins.cc | ||
regexp.cc | ||
testcfg.py | ||
wasm_corpus.tar.gz.sha1 | ||
wasm-async.cc | ||
wasm-code.cc | ||
wasm-compile.cc | ||
wasm-fuzzer-common.cc | ||
wasm-fuzzer-common.h | ||
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
foo
in 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 +_fuzzer
so 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 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/reference.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