[MPlayer-dev-eng] [PATCH] Fix uninitialized memory read in vd_ffmpeg.c

[Reimar Döffinger]

On Wed, Mar 09, 2011 at 07:49:39PM +0100, Tobias Diedrich wrote:
> Fix uninitialized memory read.
> 
> The debug message shouldn't show uninitialized bogus data if len is <= 16.
> 
> Index: mplayer-patchset1/libmpcodecs/vd_ffmpeg.c
> ===================================================================
> --- mplayer-patchset1.orig/libmpcodecs/vd_ffmpeg.c	2011-02-18 20:08:07.965376000 +0100
> +++ mplayer-patchset1/libmpcodecs/vd_ffmpeg.c	2011-02-18 20:09:34.748589000 +0100
> @@ -828,8 +828,12 @@
>  
>      avctx->hurry_up=(flags&3)?((flags&2)?2:1):0;
>  
> -    mp_msg(MSGT_DECVIDEO, MSGL_DBG2, "vd_ffmpeg data: %04x, %04x, %04x, %04x\n",
> -           ((int *)data)[0], ((int *)data)[1], ((int *)data)[2], ((int *)data)[3]);
> +    if (len >= 16) {
> +        mp_msg(MSGT_DECVIDEO, MSGL_DBG2,
> +               "vd_ffmpeg data: %04x, %04x, %04x, %04x\n",
> +               ((int *)data)[0], ((int *)data)[1],
> +               ((int *)data)[2], ((int *)data)[3]);
> +    }

Required padding is 32 bytes, so this will not use uninitialized data
(unless len is 0 and data NULL I guess -  seems like that has never happened
so far though).
Since in addition this change means you can no longer debug packages shorter
than 16 bytes I'm rather against it.