[FFmpeg-devel] [PATCH] avcodec/notchlc: Check available space for luma block code

[Paul B Mahol]

On Sat, Sep 12, 2020 at 06:43:30PM +0200, Michael Niedermayer wrote:
> Fixes: Timeout (too long -> 2sec)
> Fixes: 25439/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_NOTCHLC_fuzzer-5688211127664640
> 
> 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/notchlc.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/libavcodec/notchlc.c b/libavcodec/notchlc.c
> index 3f7079da70..e7e69b0c21 100644
> --- a/libavcodec/notchlc.c
> +++ b/libavcodec/notchlc.c
> @@ -229,6 +229,9 @@ static int decode_blocks(AVCodecContext *avctx, AVFrame *p, ThreadFrame *frame,
>      bytestream2_seek(&rgb, s->y_data_row_offsets, SEEK_SET);
>      bytestream2_seek(gb, s->y_control_data_offset, SEEK_SET);
>  
> +    if ((avctx->height + 3) / 4 * ((avctx->width + 3) / 4) * 4 > bytestream2_get_bytes_left(gb))
> +        return AVERROR_INVALIDDATA;
> +
>      dsty = (uint16_t *)p->data[0];
>      dsta = (uint16_t *)p->data[3];
>      ylinesize = p->linesize[0] / 2;
> -- 
> 2.17.1

Is this correct at all?

If you do not like timeouts than get smaller samples or reduce dimensions of accepted files.