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Michael Starzinger e5e19bf764 [wasm] Move source position tables off-heap. 
This moves source position tables associated with WasmCode objects to be
located outside the garbage-collected heap. There now is a clear link to
the source position table from code, making the one-to-one relationship
and its lifetime explicit.

R=ahaas@chromium.org
BUG=v8:7424

Change-Id: I9d0b332732508c302ba525059ef02559f45aa2f6
Reviewed-on: https://chromium-review.googlesource.com/975565
Commit-Queue: Michael Starzinger <mstarzinger@chromium.org>
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#52178}
2018-03-23 12:33:53 +00:00
..
json
multi_return [turbofan] Add fuzzer to test different signatures for multi-returns 2018-01-12 12:20:27 +00:00
parser
regexp
regexp_builtins [regexp] Initial go at a builtins fuzzer 2018-01-18 11:02:57 +00:00
wasm
wasm_async [wasm] Avoid executing infinite loops in the wasm fuzzers 2017-09-07 12:35:45 +00:00
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 [cleanup] Deprecate EnsureEventLoopInitialized 2018-02-28 15:32:28 +00:00
fuzzer-support.h [fuzzer] Use std::unique_ptr for the FuzzerSupport 2017-11-29 16:36:23 +00:00
fuzzer.cc [test/fuzzer] Fix cpplint complaints 2017-09-04 10:45:21 +00:00
fuzzer.isolate [wasm] [fuzzer] Remove wasm_call fuzzer 2018-02-01 14:30:49 +00:00
fuzzer.status
json.cc
multi-return.cc [wasm] Move source position tables off-heap. 2018-03-23 12:33:53 +00:00
parser.cc [test/fuzzer] Fix cpplint complaints 2017-09-04 10:45:21 +00:00
README.md [gyp] move build targets for tests to gypfiles. 2018-01-30 06:31:00 +00:00
regexp-builtins.cc [fuzzers] Ensure pattern is not interpreted as comment 2018-02-09 11:15:31 +00:00
regexp.cc [regexp] Add DotAll flag to regexp fuzzer 2017-12-19 10:06:15 +00:00
testcfg.py [wasm] [fuzzer] Remove wasm_call fuzzer 2018-02-01 14:30:49 +00:00
wasm_corpus.tar.gz.sha1
wasm-async.cc [wasm] Move ScheduledErrorThrower into wasm-js.cc file. 2018-01-30 10:57:36 +00:00
wasm-code.cc [test/fuzzer] Fix cpplint complaints 2017-09-04 10:45:21 +00:00
wasm-compile.cc [wasm] [fuzzer] Generate sequences of kWasmStmt 2018-02-02 11:26:06 +00:00
wasm-data-section.cc
wasm-function-sigs-section.cc
wasm-fuzzer-common.cc [fuzzer] Slightly improve generated test cases 2018-03-22 11:53:50 +00:00
wasm-fuzzer-common.h [wasm fuzzer] Require AST fuzzer modules to validate 2017-11-08 21:29:40 +00:00
wasm-globals-section.cc
wasm-imports-section.cc
wasm-memory-section.cc
wasm-names-section.cc
wasm-types-section.cc
wasm.cc [wasm] Move SyncCompile* and AsyncCompile* methods to WasmEngine 2018-01-18 13:27:46 +00:00

README.md

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