[FFmpeg-devel] [PATCH 2/2] avcodec/g2meet: Check for end of input in jpg_decode_block()

[Tomas Härdin]

mån 2019-09-09 klockan 22:16 +0200 skrev Michael Niedermayer:
> Fixes: Timeout (100sec -> 0.7sec)
> Fixes: 8668/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_G2M_fuzzer-5174143888130048
> 
> 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/g2meet.c | 3 +++
>  1 file changed, 3 insertions(+)
> 
> diff --git a/libavcodec/g2meet.c b/libavcodec/g2meet.c
> index 19e1c130ce..731d29a5d4 100644
> --- a/libavcodec/g2meet.c
> +++ b/libavcodec/g2meet.c
> @@ -244,6 +244,9 @@ static int jpg_decode_block(JPGContext *c, GetBitContext *gb,
>      const int is_chroma = !!plane;
>      const uint8_t *qmat = is_chroma ? chroma_quant : luma_quant;
>  
> +    if (get_bits_left(gb) < 1)
> +        return AVERROR_INVALIDDATA;
> +
>      c->bdsp.clear_block(block);
>      dc = get_vlc2(gb, c->dc_vlc[is_chroma].table, 9, 3);

Why doesn't the VLC stuff have EOF handling? There's bound to be a
metric bajillion of cases like this strewn across the codebase..

/Tomas