[wasmtime] initial integration

[jfoote]

Hello all,

This is an initial PR for wasmtime Rust fuzz targets, as discussed on #3285. (Bytecode Alliance tracking issue).

I didn't see clear consensus on whether to use the cargo-fuzz-bundled libfuzzer or linking the oss-fuzz version via LIB_FUZZING_ENGINE_DEPRECATED, so I left the code as-is using LIB_FUZZING_ENGINE_DEPRECATED for now. Pardon if I misunderstood there -- if we should change it for this PR or anytime please just let me know.

cc @fitzgen @jonathanmetzman

Thanks,
Jon

[jonathanmetzman]

LGTM

[jonathanmetzman]

Will wait for travis to finish to merge

[jonathanmetzman]

Hello all,

This is an initial PR for wasmtime Rust fuzz targets, as discussed on #3285. (Bytecode Alliance tracking issue).

I didn't see clear consensus on whether to use the cargo-fuzz-bundled libfuzzer or linking the oss-fuzz version via LIB_FUZZING_ENGINE_DEPRECATED, so I left the code as-is using LIB_FUZZING_ENGINE_DEPRECATED for now. Pardon if I misunderstood there -- if we should change it for this PR or anytime please just let me know.

Sorry for not being clear. You should leave as is and use LIB_FUZZING_ENGINE_DEPRECATED.

[jonathanmetzman]

I think we want to specify libfuzzer under engines otherwise honggfuzz and afl builds will be done as well.

[jonathanmetzman]

The libFuzzer ASAN build passed last time: https://travis-ci.org/google/oss-fuzz/jobs/641563087?utm_medium=notification&utm_source=github_status

[TravisBuddy]

Hey @jfoote,
Your changes look good to me!

View build log

TravisBuddy Request Identifier: c3720f80-3f05-11ea-9468-7fcc00232609

[jfoote]

If you need anything else here just LMK.

[jonathanmetzman]

Don't need anything else. Sorry I didn't get to merge this before the weekend.

[jonathanmetzman]

Looks like build is failing.
https://oss-fuzz-build-logs.storage.googleapis.com/log-336d15f7-d5fb-4db2-ae8a-49e9b990147a.txt

We (OSS-Fuzz devs) probably need to look into this since it passed on travis.

[jfoote]

Thanks for looking into this @jonathanmetzman and @alexcrichton! For posterity, @alexcrichton is taking a shot at fixing this issue in #3298.

The build succeeds for me locally, both for a9febdf (tested previously) and Alex's alexcrichton@1365cfd (tested presently).

It is not clear to me why this is failing. I noted that msan-builder is referenced in the build log but we intended to build the fuzz target only with asan. I'm not sure if that is related to the issue though. It isn't clear to me why building with msan would be generating the error that the build exits on regardless.