v8/test/fuzzer
Andreas Haas bb253d28f4 [fuzzer] Handle more than 256 parameters of the same type
The multi-return fuzzer was able to generate more than 256 parameters of
the same type. However, the fuzzer itself could not deal with so many
parameters. With this change more than 256 parameters of the same type
can be handled and tested.

R=clemensh@chromium.org

Bug: chromium:807862
Change-Id: I6941eb0ff7e78a8feebc437624fa100adeda4e3d
Reviewed-on: https://chromium-review.googlesource.com/897673
Reviewed-by: Andreas Haas <ahaas@chromium.org>
Reviewed-by: Clemens Hammacher <clemensh@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#51089}
2018-02-05 09:04:40 +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
wasm_data_section [wasm] Write fuzzers for single wasm sections. 2016-09-14 11:17:53 +00:00
wasm_function_sigs_section [wasm] Write fuzzers for single wasm sections. 2016-09-14 11:17:53 +00:00
wasm_globals_section [wasm] Write fuzzers for single wasm sections. 2016-09-14 11:17:53 +00:00
wasm_imports_section [wasm] Write fuzzers for single wasm sections. 2016-09-14 11:17:53 +00:00
wasm_memory_section [wasm] Write fuzzers for single wasm sections. 2016-09-14 11:17:53 +00:00
wasm_names_section [wasm] Write fuzzers for single wasm sections. 2016-09-14 11:17:53 +00:00
wasm_types_section [wasm] Write fuzzers for single wasm sections. 2016-09-14 11:17:53 +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 [fuzzer] Declare LLVMFuzzerInitialize with attributes only if V8_OS_MACOSX. 2017-12-19 19:44:20 +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 Add a library suitable for libfuzzer with a small unit test runner shell 2016-01-26 10:39:03 +00:00
json.cc Add GC request to libFuzzers in attempt to avoid parasitic coverage. 2016-04-28 13:32:28 +00:00
multi-return.cc [fuzzer] Handle more than 256 parameters of the same type 2018-02-05 09:04:40 +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] Add hash to regexp-builtins CHECK 2018-01-31 12:39:36 +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] Move the wasm fuzzer corpus to a different directory 2017-04-28 23:29:41 +00:00
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 add gn jumbo build support 2017-08-09 09:05:29 +00:00
wasm-function-sigs-section.cc add gn jumbo build support 2017-08-09 09:05:29 +00:00
wasm-fuzzer-common.cc [wasm] [fuzzer] Include globals and exports in generated test case 2018-02-02 09:34:30 +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 add gn jumbo build support 2017-08-09 09:05:29 +00:00
wasm-imports-section.cc add gn jumbo build support 2017-08-09 09:05:29 +00:00
wasm-memory-section.cc add gn jumbo build support 2017-08-09 09:05:29 +00:00
wasm-names-section.cc add gn jumbo build support 2017-08-09 09:05:29 +00:00
wasm-types-section.cc add gn jumbo build support 2017-08-09 09:05:29 +00:00
wasm.cc [wasm] Move SyncCompile* and AsyncCompile* methods to WasmEngine 2018-01-18 13:27:46 +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