[FFmpeg-devel] [PATCH 3/5] avcodec/decode: Check progress before dereferencing

[Michael Niedermayer]

On Tue, Jun 25, 2024 at 09:51:32PM +0200, Andreas Rheinhardt wrote:
> Michael Niedermayer:
> > On Sat, Apr 27, 2024 at 01:13:54PM +0200, Andreas Rheinhardt wrote:
> >> Michael Niedermayer:
> >>> Fixes: NULL pointer dereference
> >>> Fixes: 68192/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VP8_fuzzer-6180311026171904
> >>>
> >>> Found-by: continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
> >>> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> >>> ---
> >>>  libavcodec/decode.c | 2 ++
> >>>  1 file changed, 2 insertions(+)
> >>>
> >>> diff --git a/libavcodec/decode.c b/libavcodec/decode.c
> >>> index d031b1ca176..a6131941f43 100644
> >>> --- a/libavcodec/decode.c
> >>> +++ b/libavcodec/decode.c
> >>> @@ -1744,6 +1744,8 @@ void ff_progress_frame_report(ProgressFrame *f, int n)
> >>>  
> >>>  void ff_progress_frame_await(const ProgressFrame *f, int n)
> >>>  {
> >>> +    if (!f->progress)
> >>> +        return;
> >>>      ff_thread_progress_await(&f->progress->progress, n);
> >>>  }
> >>>  
> >>
> >> Can I get the sample? I see two places in VP8 where the VP8Frame
> >> pointers are set before the actual frame inside it is properly allocated.
> >>
> >> (Actually, it was intended for this API to not support waiting on
> >> non-existent frames (i.e. let the caller check for this; in most
> >> instances, it is already guaranteed that the frame one waits one exists,
> >> so this is unnecessary for them).)
> > 
> > did you receive the sample i sent you in april ?
> > 
> > any update on this ?
> > its still crashing without this patch
> > 
> > Running: 68192/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_VP8_fuzzer-6180311026171904
> > libavcodec/decode.c:1766:44: runtime error: member access within null pointer of type 'struct ProgressInternal'
> > SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior libavcodec/decode.c:1766:44 in
> > libavcodec/threadprogress.c:72:36: runtime error: member access within null pointer of type 'ThreadProgress' (aka 'struct ThreadProgress')
> > SUMMARY: UndefinedBehaviorSanitizer: undefined-behavior libavcodec/threadprogress.c:72:36 in
> > 
> 
> Totally forgot about this. Will look into it. Thanks for the reminder.

Hello ?
this issue is still open

thx

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Breaking DRM is a little like attempting to break through a door even
though the window is wide open and the only thing in the house is a bunch
of things you dont want and which you would get tomorrow for free anyway
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