From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758200AbcH3Su3 (ORCPT ); Tue, 30 Aug 2016 14:50:29 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57204 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753657AbcH3Su0 (ORCPT ); Tue, 30 Aug 2016 14:50:26 -0400 Date: Tue, 30 Aug 2016 14:50:21 -0400 From: Richard Guy Briggs To: Mateusz Guzik Cc: Konstantin Khlebnikov , ebiederm@xmission.com, oleg@redhat.com, sgrubb@redhat.com, pmoore@redhat.com, eparis@redhat.com, luto@amacapital.net, linux-audit@redhat.com, linux-kernel@vger.kernel.org, Al Viro Subject: Re: [PATCHv2 0/2] introduce get_task_exe_file and use it to fix audit_exe_compare Message-ID: <20160830185021.GL5983@madcap2.tricolour.ca> References: <1471962039-14940-1-git-send-email-mguzik@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1471962039-14940-1-git-send-email-mguzik@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.29]); Tue, 30 Aug 2016 18:50:26 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2016-08-23 16:20, Mateusz Guzik wrote: > audit_exe_compare directly accesses mm->exe_file without making sure the > object is stable. Fixing it using current primitives results in > partially duplicating what proc_exe_link is doing. > > As such, introduce a trivial helper which can be used in both places and > fix the func. > > Changes since v1: > * removed an unused 'out' label which crept in > > Mateusz Guzik (2): > mm: introduce get_task_exe_file > audit: fix exe_file access in audit_exe_compare The task_lock affects a much bigger struct than the mm ref count. Is this really necessary? Is a spin-lock significantly lower cost than a refcount? Other than that, this refactorization looks sensible. Acked-by: Richard Guy Briggs > fs/proc/base.c | 7 +------ > include/linux/mm.h | 1 + > kernel/audit_watch.c | 8 +++++--- > kernel/fork.c | 23 +++++++++++++++++++++++ > 4 files changed, 30 insertions(+), 9 deletions(-) > > -- > 1.8.3.1 > - RGB -- Richard Guy Briggs Kernel Security Engineering, Base Operating Systems, Red Hat Remote, Ottawa, Canada Voice: +1.647.777.2635, Internal: (81) 32635