[FFmpeg-devel] [PATCH 2/2] avcodec/vp3: Check that theora is theora

[Reimar Döffinger]

On 22.07.2019, at 01:25, Michael Niedermayer <michael at niedermayer.cc> wrote:

> Fixes: Timeout (2min -> 100ms)
> Fixes: 15366/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_THEORA_fuzzer-5737849938247680
> 
> 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/vp3.c | 2 ++
> 1 file changed, 2 insertions(+)
> 
> diff --git a/libavcodec/vp3.c b/libavcodec/vp3.c
> index a6f759ebf5..8a165c1275 100644
> --- a/libavcodec/vp3.c
> +++ b/libavcodec/vp3.c
> @@ -2957,6 +2957,8 @@ static int theora_decode_header(AVCodecContext *avctx, GetBitContext *gb)
>     s->theora_header = 0;
>     s->theora = get_bits_long(gb, 24);
>     av_log(avctx, AV_LOG_DEBUG, "Theora bitstream version %X\n", s->theora);
> +    if (!s->theora)
> +        return AVERROR_INVALIDDATA;

That seems rather strict, a 1-bit error in this field and we don't even try?
Maybe set to 1 instead with a request for sample?