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Date: Mon, 4 Oct 2010 15:05:12 -0400 (EDT)
From: Josh Bressers <bressers@...hat.com>
To: oss-security@...ts.openwall.com
Subject: Re: Small exposure in ocfs2 fast symlinks.

----- "Joel Becker" <Joel.Becker@...cle.com> wrote:

> Hey Everyone,
> 	We just discovered that ocfs2 could walk off the end of fast symlinks
> 	-- that is, symlinks that are stored directly in the inode block.
> 	ocfs2 terminates these with NUL characters, but a disk corruption or an
> 	attacker with direct access to the ocfs2 disk could overwrite the NUL.
> 	Following the symlink via the filesystem would walk off the end of the
> 	in-memory block buffer.  We're not sure how exploitable this is, but I
> 	figured I'd provide a heads-up.  The fix is in ocfs2's git tree and
> 	will be sent upstream tonight.  Erratas with the fix are being built.
> 	If someone thinks we should have a CVE, please provide me with the
> 	number.  Otherwise, just FYI.
> 

Unless someone asks for an ID, I don't plan to give this one. I dare say if
an attacker can modify the disk directly, you probably have far bigger
worries here than following symlinks.

Thanks.

-- 
    JB

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