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 Download attachment "signature.asc" of type "application/pgp-signature" (199 bytes)
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