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Date: Fri, 4 Mar 2011 22:58:27 +0200
Message-ID: <AANLkTimvhHxsMCf2FX0O8VqksOa2EAMz=S_C3LQKvE60@mail.gmail.com>
Subject: Re: [PATCH] Make /proc/slabinfo 0400
From: Pekka Enberg <penberg@kernel.org>
To: Dan Rosenberg <drosenberg@vsecurity.com>
Cc: Matt Mackall <mpm@selenic.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Dave Hansen <dave@linux.vnet.ibm.com>, Theodore Tso <tytso@mit.edu>,
        cl@linux-foundation.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
        Andrew Morton <akpm@linux-foundation.org>
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On Fri, Mar 4, 2011 at 10:37 PM, Dan Rosenberg <drosenberg@vsecurity.com> wrote:
> This patch makes these techniques more difficult by making it hard to
> know whether the last attacker-allocated object resides before a free or
> allocated object. ?Especially with vulnerabilities that only allow one
> attempt at exploitation before recovery is needed to avoid trashing too
> much heap state and causing a crash, this could go a long way. ?I'd
> still argue in favor of removing the ability to know how many objects
> are used in a given slab, since randomizing objects doesn't help if you
> know every object is allocated.

So if the attacker knows every object is allocated, how does that help
if we're randomizing the initial freelist?
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