[FFmpeg-devel] [PATCH 5/6] avcodec/ffv1dec: consider run increase in minimal golomb frame size

[Andreas Rheinhardt]

Michael Niedermayer:
> On Tue, Jul 19, 2022 at 08:37:38AM -0300, James Almer wrote:
>>
>>
>> On 7/19/2022 8:34 AM, Michael Niedermayer wrote:
>>> Fixes: Timeout
>>> Fixes: 49160/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_FFV1_fuzzer-5672826144686080
>>>
>>> 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/ffv1dec.c | 6 +++++-
>>>   1 file changed, 5 insertions(+), 1 deletion(-)
>>>
>>> diff --git a/libavcodec/ffv1dec.c b/libavcodec/ffv1dec.c
>>> index 01ddcaa512..9bdac0be4e 100644
>>> --- a/libavcodec/ffv1dec.c
>>> +++ b/libavcodec/ffv1dec.c
>>> @@ -883,7 +883,11 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *rframe,
>>>           if (buf_size < avctx->width * avctx->height / (128*8))
>>>               return AVERROR_INVALIDDATA;
>>>       } else {
>>> -        if (buf_size < avctx->height / 8)
>>> +        int i;
>>
>> for (int i...
> 
> will apply with that change
> 
> thx
> 

James' suggestion made you use an uninitialized i in the actual check;
and even the original check is wrong, as one can overrun ff_log2_run
(unless there is a check that I am not missing). So it seems to me that
reverting 15785e044ee1265464bb4f3ed727e2a8074f97b4 is appropriate.

- Andreas