Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932460AbYBNVCU (ORCPT ); Thu, 14 Feb 2008 16:02:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754148AbYBNVCF (ORCPT ); Thu, 14 Feb 2008 16:02:05 -0500 Received: from pentafluge.infradead.org ([213.146.154.40]:53378 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754021AbYBNVCD (ORCPT ); Thu, 14 Feb 2008 16:02:03 -0500 Date: Thu, 14 Feb 2008 13:00:03 -0800 From: Arjan van de Ven To: Ingo Molnar Cc: pageexec@freemail.hu, Sam Ravnborg , linux-kernel@vger.kernel.org, torvalds@linux-foundation.org, Thomas Gleixner , "H. Peter Anvin" Subject: Re: [x86.git#mm] stack protector fixes, vmsplice exploit Message-ID: <20080214130003.4d40d938@laptopd505.fenrus.org> In-Reply-To: <20080214202535.GA25316@elte.hu> References: <20080214190050.GA32258@elte.hu> <47B4AAB8.106.FEA5232@pageexec.freemail.hu> <20080214202535.GA25316@elte.hu> Organization: Intel X-Mailer: Claws Mail 3.2.0 (GTK+ 2.12.5; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 920 Lines: 25 On Thu, 14 Feb 2008 21:25:35 +0100 Ingo Molnar wrote: > > * pageexec@freemail.hu wrote: > > > really, the best defense is to reduce the useful lifetime of any > > leaked canary, and you can't get better than syscall granularity > > without disproportional effort and impact elsewhere (and i'm sure > > some would find even this disproportional ;). > > hm, i think per syscall canaries are really expensive. it's not that bad. Assuming you use a PNR that you re-seed periodically, it's * go to the next random number with PNR * write to PDA and task struct give or take 10 cycles total if you squeeze it hard, 20 if you don't. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/