v8/test/fuzzer
Leszek Swirski 146f5375da Reland "[parser] Introduce UnoptimizedCompileFlags"
This is a reland of d91679bf3a

This reland adds initializers for the output flags.

Original change's description:
> [parser] Introduce UnoptimizedCompileFlags
>
> UnoptimizedCompileFlags defines the input flags shared between parse and
> compile (currently parse-only). It is set initially with some values, and
> is immutable after being passed to ParseInfo (ParseInfo still has getters
> for the fields, but no setters).
>
> Since a few of the existing flags were output flags, ParseInfo now has a
> new output_flags field, which will eventually migrate to a ParseOutputs
> structure.
>
> Bug: v8:10314
> Change-Id: If3890a5fad883bca80a97bf9dfe44d91797dc286
> Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2096580
> Commit-Queue: Leszek Swirski <leszeks@chromium.org>
> Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
> Reviewed-by: Simon Zünd <szuend@chromium.org>
> Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#66782}

Bug: v8:10314
Change-Id: Ibade9658d99fa928709b3d56762c4c002ffff0dc
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/2111213
Commit-Queue: Leszek Swirski <leszeks@chromium.org>
Reviewed-by: Simon Zünd <szuend@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Reviewed-by: Ulan Degenbaev <ulan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#67241}
2020-04-20 15:15:07 +00:00
..
json Add json fuzzer 2016-02-02 11:29:01 +00:00
multi_return [turbofan] Add fuzzer to test different signatures for multi-returns 2018-01-12 12:20:27 +00:00
parser Add a library suitable for libfuzzer with a small unit test runner shell 2016-01-26 10:39:03 +00:00
regexp [regexp] add fuzzer support for regexp parser and compiler. 2016-02-01 14:00:38 +00:00
regexp_builtins [regexp] Initial go at a builtins fuzzer 2018-01-18 11:02:57 +00:00
wasm [wasm] Cleanup the wasm fuzzer corpus files. 2017-05-19 09:21:16 +00:00
wasm_async [wasm] Avoid executing infinite loops in the wasm fuzzers 2017-09-07 12:35:45 +00:00
wasm_code [wasm] Create a new fuzzer for wasm code. 2016-08-29 13:56:00 +00:00
wasm_compile [wasm] Syntax- and Type-aware Fuzzer 2017-02-17 17:06:29 +00:00
BUILD.gn [fuzzer] Remove the wasm section fuzzers 2019-01-11 15:18:47 +00:00
DEPS Add a library suitable for libfuzzer with a small unit test runner shell 2016-01-26 10:39:03 +00:00
fuzzer-support.cc Replace base::make_unique by std::make_unique 2019-09-10 11:21:51 +00:00
fuzzer-support.h [iwyu] Add missing includes of <memory> for std::unique_ptr 2019-09-13 17:13:36 +00:00
fuzzer.cc [test/fuzzer] Fix cpplint complaints 2017-09-04 10:45:21 +00:00
fuzzer.status Remove 'embedded_builtins' variant 2019-10-22 12:58:02 +00:00
json.cc [fuzzer] Fix OOM in v8_json_parser_fuzzer due to unnecessary long input. 2018-07-17 14:25:27 +00:00
multi-return.cc [wasm] Turn ValueType from an enum to a class 2020-03-12 17:03:16 +00:00
parser.cc Reland "[parser] Introduce UnoptimizedCompileFlags" 2020-04-20 15:15:07 +00:00
README.md [gyp] move build targets for tests to gypfiles. 2018-01-30 06:31:00 +00:00
regexp-builtins.cc [api] Create v8::String::NewFromLiteral that returns Local<String> 2020-03-09 12:02:07 +00:00
regexp.cc [regexp] Further narrow public API and restrict includes to regexp.h 2019-06-18 12:23:16 +00:00
testcfg.py Reland "Reland "[test] refactor testsuite configuration"" 2019-02-06 09:02:09 +00:00
wasm_corpus.tar.gz.sha1 [wasm] Move the wasm fuzzer corpus to a different directory 2017-04-28 23:29:41 +00:00
wasm-async.cc [weakrefs] Call Isolate::ClearKeptObjects() as part of microtask checkpoint 2020-02-19 02:25:34 +00:00
wasm-code.cc [wasm] Remove non-const reference args from fuzzers 2019-07-08 13:46:46 +00:00
wasm-compile.cc [wasm-simd][fuzzer] Add S8x16Shuffle to fuzzer 2020-04-09 01:02:57 +00:00
wasm-fuzzer-common.cc [wasm] Turn ValueType from an enum to a class 2020-03-12 17:03:16 +00:00
wasm-fuzzer-common.h [iwyu] Add missing includes of <memory> for std::unique_ptr 2019-09-13 17:13:36 +00:00
wasm.cc [wasm] Bring memory limits up to spec 2020-02-24 11:00:16 +00:00

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.

  1. 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
  2. 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
  3. 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") and v8_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

  4. 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
  5. Copy the binary name and the test directory name in test/fuzzer/fuzzer.isolate

  6. 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
  7. 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.

  1. 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 a dictionary , or a seed_corpus. See chromium-fuzzing-getting-started for more information.

  2. 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

  3. Run the fuzzer locally

    • mkdir /tmp/empty_corpus && out/libfuzzer/v8_foo_fuzzer /tmp/empty_corpus