v8/test/fuzzer
Clemens Backes 46e95920e4 [flags] Disable flags freezing in tests, fuzzers, and others
This CL explicitly disables the --freeze-flags-after-init flag for cases
where we modify flags after initialization. This is only tests, fuzzers,
and special options to d8, thus not security relevant.

These should be the last blockers for enabling the flag globally.

R=cbruni@chromium.org

Bug: v8:12887
Change-Id: I1d8a03dcc20e524d30c967f6fe15f6401de77612
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3706619
Reviewed-by: Camillo Bruni <cbruni@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#81179}
2022-06-15 11:52:46 +00:00
..
inspector [inspector-test] Gracefully handle termination. 2022-03-21 12:36:59 +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] Install the exception constructor in InstallConditionalFeatures 2021-03-25 16:28:53 +00:00
wasm_async [wasm][fuzzer] Fix return value of interpreter 2020-08-13 10:08:53 +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
wasm_streaming [wasm][streaming] Check for illegal section code 2022-06-10 14:23:07 +00:00
BUILD.gn [no-wasm] Exclude more targets from build 2021-03-09 11:25:54 +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 [flags] Disable flags freezing in tests, fuzzers, and others 2022-06-15 11:52:46 +00:00
fuzzer-support.h Reland "[include] Split out v8.h" 2021-08-24 13:08:55 +00:00
fuzzer.cc [test/fuzzer] Fix cpplint complaints 2017-09-04 10:45:21 +00:00
fuzzer.status [debug] Cleanup properly when microtask execution is terminated. 2022-02-18 08:49:05 +00:00
inspector-fuzzer.cc Fix name collision of v8::internal::IsolateData 2021-08-25 08:45:53 +00:00
json.cc Reland "[include] Split out v8.h" 2021-08-24 13:08:55 +00:00
multi-return.cc [isolate][cleanup] Remove pointer to WasmEngine 2021-06-21 09:09:25 +00:00
parser.cc [compiler] Introduce ReusableUnoptimizedCompileState 2021-12-08 11:14:27 +00:00
README.md [gyp] move build targets for tests to gypfiles. 2018-01-30 06:31:00 +00:00
regexp-builtins.cc Replace STATIC_ASSERT with static_assert 2022-05-13 13:46:27 +00:00
regexp.cc [cleanup] Fix -Wshadow warnings in test/fuzzer/regexp 2021-09-27 15:59:54 +00:00
testcfg.py [wasm] Fix error printing in streaming fuzzer 2022-06-09 07:34:05 +00:00
wasm_corpus.tar.gz.sha1 [wasm] Update fuzzer corpus 2022-01-12 16:47:30 +00:00
wasm-async.cc Reland "[include] Split out v8.h" 2021-08-24 13:08:55 +00:00
wasm-code.cc [fuzzer] Add struct type and array type to fuzzed module 2021-07-19 10:59:15 +00:00
wasm-compile.cc [wasm] Various small cleanups 2022-06-07 13:13:45 +00:00
wasm-fuzzer-common.cc [stringrefs] Implement string.const 2022-06-08 16:49:14 +00:00
wasm-fuzzer-common.h [fuzzer] Add struct type and array type to fuzzed module 2021-07-19 10:59:15 +00:00
wasm-streaming.cc [wasm] Fix error printing in streaming fuzzer 2022-06-09 07:34:05 +00:00
wasm.cc Reland "[include] Split out v8.h" 2021-08-24 13:08:55 +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