From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754929Ab2G3Vtg (ORCPT ); Mon, 30 Jul 2012 17:49:36 -0400 Received: from lxorguk.ukuu.org.uk ([81.2.110.251]:53673 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754698Ab2G3Vte (ORCPT ); Mon, 30 Jul 2012 17:49:34 -0400 Date: Mon, 30 Jul 2012 22:50:37 +0100 From: Alan Cox To: John Johansen Cc: Kees Cook , linux-kernel@vger.kernel.org, James Morris , linux-security-module@vger.kernel.org Subject: Re: [PATCH] Yama: access current->comm directly Message-ID: <20120730225037.4c8dd450@ultron> In-Reply-To: <5016FADD.1030503@canonical.com> References: <20120730165848.GA28288@www.outflux.net> <5016FADD.1030503@canonical.com> X-Mailer: Claws Mail 3.8.0 (GTK+ 2.24.8; x86_64-redhat-linux-gnu) Face: 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 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 30 Jul 2012 14:21:33 -0700 John Johansen wrote: > On 07/30/2012 09:58 AM, Kees Cook wrote: > > The core ptrace access checking routine already holds the task lock, > > so there is no need to use get_task_comm() which just tries to take the > > lock again. Drop its use and access current->comm directly. > > > > Reported-by: Fengguang Wu > > Suggested-by: Oleg Nesterov > > Cc: stable@vger.kernel.org > > Signed-off-by: Kees Cook > yep, looks good > > Acked-by: John Johansen Code looks correct but having a weird cornercase direct reference is asking for an accident later. For maintainability I'd rather see that as __get_task_comm() or get_task_commu_unlocked() which does the job, deals with all the edge cases and contains a WARN_ON check on the lock. Alan