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Re: CVE Requests for FFmpeg 0.9.1
From: Michael Niedermayer <michaelni () gmx at>
Date: Thu, 5 Jan 2012 19:53:51 +0100

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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