From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763386AbYETLz2 (ORCPT ); Tue, 20 May 2008 07:55:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753755AbYETLzT (ORCPT ); Tue, 20 May 2008 07:55:19 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:44365 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752974AbYETLzS (ORCPT ); Tue, 20 May 2008 07:55:18 -0400 Date: Tue, 20 May 2008 13:55:01 +0200 From: Ingo Molnar To: Avi Kivity Cc: Andrew Morton , Andi Kleen , linux-kernel@vger.kernel.org, Sam Ravnborg Subject: Re: [PATCH] Make LIST_POISON less deadly (v3) Message-ID: <20080520115501.GA6045@elte.hu> References: <1211283565-30671-1-git-send-email-avi@qumranet.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1211283565-30671-1-git-send-email-avi@qumranet.com> User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Avi Kivity wrote: > The list macros use LIST_POISON1 and LIST_POISON2 as undereferencable > pointers in order to trap erronous use of freed list_heads. > Unfortunately userspace can arrange for those pointers to actually be > dereferencable, potentially turning an oops to an expolit. > > To avoid this allow architectures (currently x86_64 only) to override > the default values for these pointers with truly-undereferncable > values. This is easy on x86_64 as the virtual address space is large > and contains unmapped ranges. looks good - thanks Avi - i've added your patch to the -tip tree. I have opened a separate topic for it: tip/safe-poison-pointers. (because it affects other architectures as well) Ingo