[FFmpeg-cvslog] alsdec: check block length

[Thilo Borgmann]

Am 16.01.14 21:43, schrieb Reinhard Tartler:
> ffmpeg | branch: release/0.10 | Reinhard Tartler <siretart at tauware.de> | Sun Dec  8 13:24:26 2013 -0500| [d4a24e43edd0c1a06d5dbf454448fde5b3d1d281] | committer: Reinhard Tartler
> 
> alsdec: check block length
> 
> Fix writing over the end
> 
> Found-by: Mateusz "j00ru" Jurczyk and Gynvael Coldwind
> Addresses: CVE-2013-0845
> (cherry picked from commit 2a0fb7286d67c47e44aa76c237ede117b22af616)
> 
> Signed-off-by: Reinhard Tartler <siretart at tauware.de>
> (cherry picked from commit 3f7d89034bfe50893927cc92ddcb95a2e9b4178d)
> Signed-off-by: Reinhard Tartler <siretart at tauware.de>
> 
>> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=d4a24e43edd0c1a06d5dbf454448fde5b3d1d281
> ---
> 
>  libavcodec/alsdec.c |    5 +++++
>  1 file changed, 5 insertions(+)
> 
> diff --git a/libavcodec/alsdec.c b/libavcodec/alsdec.c
> index b0369d7..7daa545 100644
> --- a/libavcodec/alsdec.c
> +++ b/libavcodec/alsdec.c
> @@ -1386,6 +1386,11 @@ static int read_frame_data(ALSDecContext *ctx, unsigned int ra_frame)
>  
>          for (b = 0; b < ctx->num_blocks; b++) {
>              bd.block_length = div_blocks[b];
> +            if (bd.block_length <= 0) {
> +                av_log(ctx->avctx, AV_LOG_WARNING,
> +                       "Invalid block length %d in channel data!\n", bd.block_length);
> +                continue;
> +            }

Have you tested this? Does FATE complain?
IIRC a block length == 0 is valid for example in the last frame.

-Thilo