linux-kernel - Re: [PATCH] Make /proc/slabinfo 0400

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Message-ID: <AANLkTimvhHxsMCf2FX0O8VqksOa2EAMz=S_C3LQKvE60@mail.gmail.com>
Date:	Fri, 4 Mar 2011 22:58:27 +0200
From:	Pekka Enberg <penberg@...nel.org>
To:	Dan Rosenberg <drosenberg@...curity.com>
Cc:	Matt Mackall <mpm@...enic.com>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Dave Hansen <dave@...ux.vnet.ibm.com>,
	Theodore Tso <tytso@....edu>, cl@...ux-foundation.org,
	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Ingo Molnar <mingo@...e.hu>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH] Make /proc/slabinfo 0400

On Fri, Mar 4, 2011 at 10:37 PM, Dan Rosenberg <drosenberg@...curity.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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