From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753684Ab2A0U2T (ORCPT ); Fri, 27 Jan 2012 15:28:19 -0500 Received: from fgwmail5.fujitsu.co.jp ([192.51.44.35]:48699 "EHLO fgwmail5.fujitsu.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751477Ab2A0U2S (ORCPT ); Fri, 27 Jan 2012 15:28:18 -0500 Message-ID: <4F230903.5080504@jp.fujitsu.com> Date: Fri, 27 Jan 2012 15:28:51 -0500 From: KOSAKI Motohiro User-Agent: Mozilla/5.0 (Windows NT 5.1; rv:9.0) Gecko/20111222 Thunderbird/9.0.1 MIME-Version: 1.0 To: keescook@chromium.org CC: gorcunov@openvz.org, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, ebiederm@xmission.com, xemul@openvz.org, mtk.manpages@gmail.com, tj@kernel.org, avagin@openvz.org, serge.hallyn@canonical.com, xemul@parallels.com, segoon@openwall.com, kamezawa.hiroyu@jp.fujitsu.com Subject: Re: [RFC c/r 4/4] c/r: prctl: Extend PR_SET_MM to set up more mm_struct entries References: <20120127175342.273260614@openvz.org> <20120127175939.928628374@openvz.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org >> + >> + case PR_SET_MM_AUXV: >> + if (arg4 > sizeof(mm->saved_auxv)) >> + goto out; >> + up_read(&mm->mmap_sem); >> + >> + error = -EFAULT; >> + if (!copy_from_user(mm->saved_auxv, (const void __user *)addr, arg4)) >> + error = 0; >> + >> + return error; > > Is the mmap_sem released here because of the copy_from_user()? Is it > still safe to write to saved_auxv? Sure. It's unsafe.