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Message-ID: <1316455395.16137.160.camel@nimitz>
Date: Mon, 19 Sep 2011 11:03:15 -0700
From: Dave Hansen <dave@...ux.vnet.ibm.com>
To: Pekka Enberg <penberg@...helsinki.fi>
Cc: Vasiliy Kulikov <segoon@...nwall.com>,
        Andrew Morton
 <akpm@...ux-foundation.org>,
        kernel-hardening@...ts.openwall.com, Kees Cook
 <kees@...ntu.com>,
        Cyrill Gorcunov <gorcunov@...il.com>,
        Al Viro
 <viro@...iv.linux.org.uk>,
        Christoph Lameter <cl@...ux-foundation.org>,
        Matt Mackall <mpm@...enic.com>, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, Dan Rosenberg <drosenberg@...curity.com>,
        Theodore Tso
 <tytso@....edu>, Alan Cox <alan@...ux.intel.com>,
        Jesper Juhl
 <jj@...osbits.net>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: Re: [RFC PATCH 2/2] mm: restrict access to
 /proc/slabinfo

On Mon, 2011-09-19 at 20:51 +0300, Pekka Enberg wrote:
> How is the attacker able to identify that we kmalloc()'d from ecryptfs or
> VFS based on non-root /proc/slabinfo when the slab allocator itself does
> not have that sort of information if you mix up the allocations? Isn't this
> much stronger protection especially if you combine that with /proc/slabinfo
> restriction? 

Mixing it up just adds noise.  It makes the attack somewhat more
difficult, but it still leaves open the possibility that the attacker
can filter out the noise somehow.

-- Dave

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