[FFmpeg-devel] [PATCH 2/3] avcodec/smacker: Check remaining bits in SMK_BLK_FULL
Andreas Rheinhardt
andreas.rheinhardt at gmail.com
Mon Oct 5 04:24:08 EEST 2020
Michael Niedermayer:
> Fixes: out of array access
> Fixes: 26047/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_SMACKER_fuzzer-5083031667474432
>
> 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/smacker.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/libavcodec/smacker.c b/libavcodec/smacker.c
> index 813eb862c0..6b1faec09e 100644
> --- a/libavcodec/smacker.c
> +++ b/libavcodec/smacker.c
> @@ -448,6 +448,8 @@ static int decode_frame(AVCodecContext *avctx, void *data, int *got_frame,
> case SMK_BLK_FULL:
> mode = 0;
> if(avctx->codec_tag == MKTAG('S', 'M', 'K', '4')) { // In case of Smacker v4 we have three modes
> + if (get_bits_left(&gb) < 1)
> + return AVERROR_INVALIDDATA;
> if(get_bits1(&gb)) mode = 1;
> else if(get_bits1(&gb)) mode = 2;
> }
>
LGTM.
(This is a file in which the type and the full tree consists of only one
entry (so that smk_get_code() never checks for overreads), isn't it? I
have to admit to have overlooked this edge case.)
- Andreas
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