[FFmpeg-devel] [PATCH] avcodec/movtextdec: Check style_start/end

[Philip Langdale]

On Sun,  8 Apr 2018 03:29:44 +0200
Michael Niedermayer <michael at niedermayer.cc> wrote:

> Limits based on 3GPP TS 26.245 V14.0.0
> Fixes: Timeout
> Fixes:
> 6377/clusterfuzz-testcase-minimized-ffmpeg_AV_CODEC_ID_MOVTEXT_fuzzer-5175929115508736
> 
> 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/movtextdec.c | 8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/libavcodec/movtextdec.c b/libavcodec/movtextdec.c
> index 89ac791602..c38c5edce6 100644
> --- a/libavcodec/movtextdec.c
> +++ b/libavcodec/movtextdec.c
> @@ -299,6 +299,14 @@ static int decode_styl(const uint8_t *tsmb,
> MovTextContext *m, AVPacket *avpkt) m->s_temp->style_start =
> AV_RB16(tsmb); tsmb += 2;
>          m->s_temp->style_end = AV_RB16(tsmb);
> +
> +        if (   m->s_temp->style_end < m->s_temp->style_start
> +            || (m->count_s && m->s_temp->style_start <
> m->s[m->count_s - 1]->style_end)) {
> +            av_freep(&m->s_temp);
> +            mov_text_cleanup(m);
> +            return AVERROR(ENOMEM);
> +        }
> +
>          tsmb += 2;
>          m->s_temp->style_fontID = AV_RB16(tsmb);
>          tsmb += 2;

LGTM.


--phil