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Date: Thu, 5 Jan 2012 19:53:51 +0100
From: Michael Niedermayer <michaelni@....at>
To: oss-security@...ts.openwall.com
Subject: Re: CVE Requests for FFmpeg 0.9.1
Hi Steven
On Thu, Jan 05, 2012 at 12:37:44PM -0500, Steven M. Christey wrote:
>
> Michael, this is a well-organized request, thank you!
>
>
> >I tried to sort the issues a little according to type to make this huge
> >list a bit less ugly. Also feel free to skip things considered too
> >minor, iam not sure where the threshold of "too minor" is.
>
> A couple thoughts on this one, I hope this makes sense.
>
> My VERY limited understanding of ffmpeg is that it is single-user,
> and it can only process a single file from a single source, without
> multiple "sessions" or "actions" using data from different sources.
> If that is the case, then crashers like NULL dereferences and
> divide-by-zero might not qualify for inclusion in CVE. With
> products like web browsers and document editors, a crash from one
> single window or tab could cause a denial of service by closing
> *other* independent windows or tabs that the user may care about;
> with things like kernels or servers, a crash affects many sessions
> and users. So if ffmpeg only processes one file at a time, a basic
> crasher probably doesn't get a CVE.
>
> If the crash is strongly associated with data integrity, e.g. memory
> corruption or invalid free's, then it would get a CVE - since we
> make a conservative assumption that a code-execution exploit *might*
> be found by someone, and the consequence might be more than DoS.
> I've been somewhat agnostic about out-of-range reads.
>
> However, such crashes that appear in the *libraries* provided by
> ffmpeg would qualify, since those libraries might be used in an
> independent product for which a crash is a security issue (for
> example, a product might use a library function to convert the audio
> for a large number of files that have been uploaded from many users,
> and a single crash prevents other users' files from being converted.
> In this way, shared libraries are treated more conservatively.)
Very well said, i fully agree.
I should have clarified this in my initial post, but
these issues IIRC are all in the ffmpeg libraries libavcodec
& libavformat. They are used by at least youtube, chrome, videolan,
our ffserver, mplayer, mencoder, xine, gstreamer and quite a few others.
[...]
--
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
I know you won't believe me, but the highest form of Human Excellence is
to question oneself and others. -- Socrates
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