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Re: [oCERT-2011-002] libavcodec insufficient boundary check
From: Daniele Bianco <danbia () ocert org>
Date: Wed, 10 Aug 2011 16:26:49 +0200

On Wed, Aug 10, 2011 at 10:04:34AM -0400, Dan Rosenberg wrote:
On Wed, Aug 10, 2011 at 9:19 AM, Daniele Bianco <danbia () ocert org> wrote:

#2011-002 libavcodec insufficient boundary check

Description:

The libavcodec library, an open source video encoding/decoding library part
of the FFmpeg and Libav projects, performs insufficient boundary check
against a buffer index. The missing check can result in arbitrary read/write
of data outside a destination buffer boundaries.

The vulnerability affects the Chinese AVS video (CAVS) file format decoder,
specially crafted CAVS files may lead to arbitrary code execution during
decoding.


While you're at it, here are a couple more:

* Out-of-bounds read on lines 166-171 due to signedness error
* Out-of-bounds read on lines 224-240 due to signedness error

Line numbers based on upstream git:
http://git.videolan.org/?p=ffmpeg.git;a=blob;f=libavcodec/cavsdec.c;h=acf040788c9a4c34807ba2efa10312b5b8e84f02;hb=6481a36010d8f7d834676f17ba555d0a3815c760


Hint to distributions and software developers: if you're going to use
libavcodec (or libavformat, etc.) for your project, consider
restricting the default build to include only *commonly* used codecs
and demuxers.  The code quality of many of the more obscure formats is
questionable at best.

Regards,
Dan

Hi Dan,
just forwarded this to the maintainer.

Cheers,
Daniele

--
  Daniele Bianco      Open Source Computer Security Incident Response Team
  <danbia () ocert org>                                  http://www.ocert.org

  GPG Key 0x9544A497
  GPG Key fingerprint = 88A7 43F4 F28F 1B9D 6F2D  4AC5 AE75 822E 9544 A497


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