[FFmpeg-devel] [OSS-Fuzz] Have you considered enabling memory sanitizer?

[Kacper Michajlow]

On Thu, 27 Jun 2024 at 02:50, Kacper Michajlow <kasper93 at gmail.com> wrote:
>
> On Thu, 27 Jun 2024 at 00:45, Michael Niedermayer
> <michael at niedermayer.cc> wrote:
> >
> > On Wed, Jun 26, 2024 at 09:07:42PM +0200, Kacper Michajlow wrote:
> > > Hi,
> > >
> > > Like in the topic. I think it would be useful to enable MSAN on
> > > OSS-Fuzz. We get some tiny issues and it would be probably good to
> > > have them tracked upstream. All infra is here, so enabling it is as
> > > simple as adding it to the project.yaml. Except libbz2.so and libz.so
> > > would have to be built inline instead, looking at the build.sh, they
> > > are prebuilt. The rest should just work (TM), but needs to be tested.
> > > You can set an "experimental' flag to have it not create issues on
> > > monorail, initially.
> >
> > I assumed ossfuzz would enable all sanitizers by default
>
> They do not do that by default, because MSAN requires all dependencies
> to be instrumented too. See
> https://google.github.io/oss-fuzz/getting-started/new-project-guide/#sanitizers
>
> Looking at build.sh for ffmpeg, it should be fine to enable it.
> Obviously I have not tested everything, but I was running some tests
> locally with MSAN and also tested it with mpv oss-fuzz builds where we
> build ffmpeg too with MSAN.
>
> - Kacper

I've sent a PR to enable MSAN and a few other build improvements.
Please take a look https://github.com/google/oss-fuzz/pull/12211

Also, would it be ok to add myself to auto_ccs for ffmpeg? Mostly to
monitor what issues are reported upstream, as we get some reports in
mpv fuzzing and I never know if I should report it upstream (ffmpeg)
or it is already found by first-party fuzzing and I shouldn't make
more noise.

- Kacper