[FFmpeg-devel] [PATCH 1/2] avcodec/agm: Test remaining data in decode_raw_intra_rgb()

[Andreas Rheinhardt]

Michael Niedermayer:
> Fixes: Timeout (270sec -> 25ms)
> Fixes: 20485/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_AGM_fuzzer-5636954207289344
> 
> 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/agm.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/libavcodec/agm.c b/libavcodec/agm.c
> index 80f4697ee5..957131648b 100644
> --- a/libavcodec/agm.c
> +++ b/libavcodec/agm.c
> @@ -573,6 +573,9 @@ static int decode_raw_intra_rgb(AVCodecContext *avctx, GetByteContext *gbyte, AV
>      uint8_t *dst = frame->data[0] + (avctx->height - 1) * frame->linesize[0];
>      uint8_t r = 0, g = 0, b = 0;
>  
> +    if (bytestream2_get_bytes_left(gbyte) < 3 * avctx->width * avctx->height)

Can the multiplication on the right overflow?

> +        return AVERROR_INVALIDDATA;
> +
>      for (int y = 0; y < avctx->height; y++) {
>          for (int x = 0; x < avctx->width; x++) {
>              dst[x*3+0] = bytestream2_get_byte(gbyte) + r;

After one has checked once that enough data is present, one can use
the unchecked bytestream2-API here and for the other two reads.

- Andreas