From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755017AbYDIIme (ORCPT ); Wed, 9 Apr 2008 04:42:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752465AbYDIIm0 (ORCPT ); Wed, 9 Apr 2008 04:42:26 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:52125 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751871AbYDIIm0 (ORCPT ); Wed, 9 Apr 2008 04:42:26 -0400 Date: Wed, 9 Apr 2008 10:42:00 +0200 From: Ingo Molnar To: Roland McGrath Cc: Thomas Gleixner , Amnon Shiloh , linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/2] x86 vdso 32-bit vdso-disabling fixes Message-ID: <20080409084200.GA32466@elte.hu> References: <20080409082703.B805926F992@magilla.localdomain> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080409082703.B805926F992@magilla.localdomain> 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 * Roland McGrath wrote: > These two patches together address two potential bugs when trying to > disable the 32-bit vDSO via sysctl or boot parameters (vdso32=0). > > Currently, every 32-bit exec gets the vDSO mapped even if it's > disabled (the process just doesn't get told about it). Because it's > in fact always there, the bug that patch 1/2 fixes cannot happen now. > With patch 2/2, it won't be mapped at all when it's disabled, which is > one of the things that people might really want when they disable it > (so nothing they didn't ask for goes into their address space). > > The 32-bit signal handler setup when SA_RESTORER is not used refers to > current->mm->context.vdso without regard to whether the vDSO has been > disabled when the process was exec'd. Patch 1/2 fixes this not to use > it when it's null, which becomes possible after patch 2/2. (This > never happens in normal use, because glibc's sigaction call uses > SA_RESTORER unless glibc detected the vDSO.) thanks Roland, applied. Ingo