v8/test/fuzzer
Andreas Haas ffee558e14 [cleanup] use unique_ptr for the DefaultPlatform
With this CL, {CreateDefaultPlatform} returns a unique_ptr to indicate
that the caller owns the returned memory. We had several memory leaks
where the memory of the DefaultPlatform did not get deallocated.

In addition, the {TracingController} of the {DefaultPlatform} also gets
received as a unique_ptr. Thereby we document that the {DefaultPlatform}
takes ownership of the {TracingController}. Note that the memory of the
{TracingController} was already owned by the {DefaultPlatform}, but it
was not documented in the interface, and it was used incorrectly in
tests.

This CL fixes the asan issues in 
https://chromium-review.googlesource.com/c/v8/v8/+/753583	
([platform] Implement TaskRunners in the DefaultPlatform)

R=rmcilroy@chromium.org

Cq-Include-Trybots: master.tryserver.chromium.linux:linux_chromium_rel_ng
Change-Id: I0d1a6d3b22bb8289dc050b1977e4f58381cec675
Reviewed-on: https://chromium-review.googlesource.com/755033
Reviewed-by: Adam Klein <adamk@chromium.org>
Reviewed-by: Jakob Gruber <jgruber@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Commit-Queue: Andreas Haas <ahaas@chromium.org>
Cr-Commit-Position: refs/heads/master@{#49349}
2017-11-14 09:57:18 +00:00
..
json
parser
regexp
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_call
wasm_code
wasm_compile [wasm] Syntax- and Type-aware Fuzzer 2017-02-17 17:06:29 +00:00
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] use unique_ptr for the DefaultPlatform 2017-11-14 09:57:18 +00:00
fuzzer-support.h [cleanup] use unique_ptr for the DefaultPlatform 2017-11-14 09:57:18 +00:00
fuzzer.cc [test/fuzzer] Fix cpplint complaints 2017-09-04 10:45:21 +00:00
fuzzer.gyp [wasm] Avoid executing infinite loops in the wasm fuzzers 2017-09-07 12:35:45 +00:00
fuzzer.isolate [wasm] Remove the wasm-asmjs fuzzer 2017-06-21 10:59:35 +00:00
fuzzer.status
json.cc
parser.cc [test/fuzzer] Fix cpplint complaints 2017-09-04 10:45:21 +00:00
README.md [fuzzer] Documentation: fix link for build configurations reference. 2017-10-05 16:45:12 +00:00
regexp.cc [regexp] Additional checks to flush out fuzzer crash 2017-08-29 15:10:30 +00:00
testcfg.py [test] Let flags from test case have precedence 2017-10-27 13:22:39 +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 compilation methods to module-compiler.h 2017-09-28 13:14:26 +00:00
wasm-call.cc [wasm] [test] [cleanup] Add missing undefs 2017-09-11 12:09:50 +00:00
wasm-code.cc [test/fuzzer] Fix cpplint complaints 2017-09-04 10:45:21 +00:00
wasm-compile.cc [wasm fuzzer] fix i64.store generation error 2017-11-09 13:20:25 +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] Clear pending exception unconditionally 2017-11-09 12:17:05 +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 compilation methods to module-compiler.h 2017-09-28 13:14:26 +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 build rules of an existing fuzzer in test/fuzzer/fuzzer.gyp, e.g. the build rules for the wasm.cc fuzzer are v8_simple_wasm_fuzzer and wasm_fuzzer_lib

    • This build rule is needed to compile with gyp
  6. Copy the binary name and the test directory name in test/fuzzer/fuzzer.isolate

  7. 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
  8. 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