From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750793AbWFWOgz (ORCPT ); Fri, 23 Jun 2006 10:36:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750794AbWFWOgy (ORCPT ); Fri, 23 Jun 2006 10:36:54 -0400 Received: from [81.2.110.250] ([81.2.110.250]:12229 "EHLO lxorguk.ukuu.org.uk") by vger.kernel.org with ESMTP id S1750793AbWFWOgx (ORCPT ); Fri, 23 Jun 2006 10:36:53 -0400 Subject: Re: [PATCH] x86_64: another fix for canonical RIPs during signal handling From: Alan Cox To: Willy Tarreau Cc: pageexec@freemail.hu, Andi Kleen , marcelo@kvack.org, linux-kernel@vger.kernel.org In-Reply-To: <20060623133217.GA24737@1wt.eu> References: <449BC808.4174.277D15CF@pageexec.freemail.hu> <449C0616.4382.286F7C8C@pageexec.freemail.hu> <20060623133217.GA24737@1wt.eu> Content-Type: text/plain Content-Transfer-Encoding: 7bit Date: Fri, 23 Jun 2006 15:51:50 +0100 Message-Id: <1151074310.4549.28.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.6.2 (2.6.2-1.fc5.5) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Ar Gwe, 2006-06-23 am 15:32 +0200, ysgrifennodd Willy Tarreau: > If I understand it well, an application which maps address 0 has no way to > be notified that the kernel detected a corrupted stack pointer. A debugger can deal with this corner case if it ever needs to be careful mapping and remapping of the page. Very few apps map data at the zero page and those that do usually map a single zero page which probably isn't PROT_EXEC anyway. (The usual case is to speed up pointer chain walking by knowing that NULL->NULL->... is always NULL) Alan