[FFmpeg-devel] [PATCH] nutdec: reject negative sm_size

[Michael Niedermayer]

On Fri, Dec 18, 2015 at 05:22:31PM +0100, Andreas Cadhalpun wrote:
> If it is negative, it makes size larger than the size of the packet
> buffer, causing invalid writes in avio_read.
> 
> Signed-off-by: Andreas Cadhalpun <Andreas.Cadhalpun at googlemail.com>
> ---
>  libavformat/nutdec.c | 5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/libavformat/nutdec.c b/libavformat/nutdec.c
> index 286d1ee..47ae7a7 100644
> --- a/libavformat/nutdec.c
> +++ b/libavformat/nutdec.c
> @@ -1146,6 +1146,11 @@ static int decode_frame(NUTContext *nut, AVPacket *pkt, int frame_code)
>              goto fail;
>          }
>          sm_size = avio_tell(bc) - pkt->pos;
> +        if (sm_size < 0) {

did sm_size overflow and should be 64bit ?
did the byte position (avio_tell) move backward ? (this should not
happen)

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Asymptotically faster algorithms should always be preferred if you have
asymptotical amounts of data
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