cd5fbf635c
This significantly reduces the build time when modifying wasm files: before touching all wasm headers required 684 steps to rebuild, now it's 216. BUG=v8:7754,v8:7490 TBR=clemensh@chromium.org, ulan@chromium.org, tebbi@chromium.org, verwaest@chromium.org, jgruber@chromium.org Cq-Include-Trybots: luci.v8.try:v8_linux_noi18n_rel_ng Change-Id: I9003b5b73ac568a29688c5f97ec718c9de8aaaef Reviewed-on: https://chromium-review.googlesource.com/1150163 Commit-Queue: Marja Hölttä <marja@chromium.org> Reviewed-by: Clemens Hammacher <clemensh@chromium.org> Reviewed-by: Marja Hölttä <marja@chromium.org> Cr-Commit-Position: refs/heads/master@{#54699} |
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.. | ||
json | ||
multi_return | ||
parser | ||
regexp | ||
regexp_builtins | ||
wasm | ||
wasm_async | ||
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 | ||
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-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
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