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Re: C file recoginzed as image file


From: Stuart D. Herring
Subject: Re: C file recoginzed as image file
Date: Mon, 8 Jan 2007 10:12:00 -0800 (PST)
User-agent: SquirrelMail/1.4.8-2.el3.7lanl

>> IIUC, Emacs relies on the image libraries in the same way as Emacs
>> relies on zlib (or is gzip?) to (un)compress *.gz files.
>
> Emacs does not use zlib for (un)compressing, it calls gzip as an external
> program.  A bug in gzip cannot affect Emacs beyond getting a stream of
> garbage bytes from it.

A bug in gzip, invoked automatically on untrusted data by Emacs, could
very easily affect Emacs by becoming the pawn of a remote program and then
A) sending Emacs SIGKILL or B) deleting the user's .emacs file or C) (in
an appropriate privilege environment) destroying the filesystem on which
emacs is stored.  A is obviously an overly literal effect, and precisely B
happening is unlikely, but the threat of scenarios like B and C is present
whether it is Emacs' memory space (via a library linked into it statically
or dynamically) in which the attack occurs or it is merely due to Emacs
that the attack can occur so automatically.

Davis

-- 
This product is sold by volume, not by mass.  If it appears too dense or
too sparse, it is because mass-energy conversion has occurred during
shipping.




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