[FFmpeg-devel] [PATCH] avformat/icodec: Fix crash probing fuzzed file

[Michael Bradshaw]

On Mon, Feb 15, 2016 at 9:57 AM, Mark Harris <mark.hsj at gmail.com> wrote:
> Avoid invalid memory read/crash when ico offset >= 0xfffffff8.
> Base64-encoded example: AAABADAwMDAwMAAAMAAwMDAw/P///w==
> ---
>  libavformat/icodec.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/libavformat/icodec.c b/libavformat/icodec.c
> index 6ddb901..8f84337 100644
> --- a/libavformat/icodec.c
> +++ b/libavformat/icodec.c
> @@ -60,7 +60,7 @@ static int probe(AVProbeData *p)
>          offset = AV_RL32(p->buf + 18 + i * 16);
>          if (offset < 22)
>              return FFMIN(i, AVPROBE_SCORE_MAX / 4);
> -        if (offset + 8 > p->buf_size)
> +        if (offset > p->buf_size - 8)

Is AVProbeData.buf_size guaranteed to be >= 8?

>              return AVPROBE_SCORE_MAX / 4 + FFMIN(i, 1);
>          if (p->buf[offset] != 40 && AV_RB64(p->buf + offset) != PNGSIG)
>              return FFMIN(i, AVPROBE_SCORE_MAX / 4);
> --
> 2.7.1
>
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