Openwall GNU/*/Linux - a small security-enhanced Linux distro for servers
[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Date: Mon, 17 Jul 2017 10:54:59 -0700
From: Matthew Wilcox <willy@...radead.org>
To: Alexander Popov <alex.popov@...ux.com>
Cc: Christoph Lameter <cl@...ux.com>, Pekka Enberg <penberg@...nel.org>,
	David Rientjes <rientjes@...gle.com>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, kernel-hardening@...ts.openwall.com,
	keescook@...omium.org
Subject: Re: [PATCH 1/1] mm/slub.c: add a naive detection of double free or
 corruption

On Mon, Jul 17, 2017 at 07:45:07PM +0300, Alexander Popov wrote:
> Add an assertion similar to "fasttop" check in GNU C Library allocator:
> an object added to a singly linked freelist should not point to itself.
> That helps to detect some double free errors (e.g. CVE-2017-2636) without
> slub_debug and KASAN. Testing with hackbench doesn't show any noticeable
> performance penalty.

>  {
> +	BUG_ON(object == fp); /* naive detection of double free or corruption */
>  	*(void **)(object + s->offset) = fp;
>  }

Is BUG() the best response to this situation?  If it's a corruption, then
yes, but if we spot a double-free, then surely we should WARN() and return
without doing anything?

Powered by blists - more mailing lists

Your e-mail address:

Powered by Openwall GNU/*/Linux - Powered by OpenVZ