Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751539Ab2BOPKQ (ORCPT ); Wed, 15 Feb 2012 10:10:16 -0500 Received: from mail-bk0-f46.google.com ([209.85.214.46]:45063 "EHLO mail-bk0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750915Ab2BOPKM (ORCPT ); Wed, 15 Feb 2012 10:10:12 -0500 Date: Wed, 15 Feb 2012 19:10:08 +0400 From: Cyrill Gorcunov To: Oleg Nesterov Cc: "Eric W. Biederman" , Pavel Emelyanov , Andrey Vagin , KOSAKI Motohiro , Ingo Molnar , "H. Peter Anvin" , Thomas Gleixner , Glauber Costa , Andi Kleen , Tejun Heo , Matt Helsley , Pekka Enberg , Eric Dumazet , Vasiliy Kulikov , Alexey Dobriyan , Valdis.Kletnieks@vt.edu, Michal Marek , Frederic Weisbecker , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: + syscalls-x86-add-__nr_kcmp-syscall-v8.patch added to -mm tree Message-ID: <20120215151008.GL1894@moon> References: <20120215143606.GA14037@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120215143606.GA14037@redhat.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1304 Lines: 40 On Wed, Feb 15, 2012 at 03:36:06PM +0100, Oleg Nesterov wrote: > > task->files can be NULL, we can race with exit_files(). So I need to call get_files_struct. Thanks Oleg! > > > + fdt = files_fdtable(task->files); > > + if (idx < fdt->max_fds) > > + file = fdt->fd[idx]; > > You can probably rely on rcu instead of ->file_lock, but this is minor. > I think so. I'll be updating the patch anyway (on top of current one) so I'll address this comment too. Thanks! > > + > > + /* > > + * One should have enough rights to inspect task details. > > + */ > > + if (!ptrace_may_access(task1, PTRACE_MODE_READ) || > > + !ptrace_may_access(task2, PTRACE_MODE_READ)) { > > + ret = -EACCES; > > Well, probably this is fine... but may be you can add a comment. > The task can change its credentials right after ptrace_may_access() > succeeds. This _looks_ wrong, perhaps it makes sense to add the > "we do not care" note. > Wait, how it's differ from other ptrace_may_access calls all over the kernel? I suppose I'm missing something obvious? Cyrill -- 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/