From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753516Ab2CaV1P (ORCPT ); Sat, 31 Mar 2012 17:27:15 -0400 Received: from shards.monkeyblade.net ([198.137.202.13]:36580 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752922Ab2CaV1N convert rfc822-to-8bit (ORCPT ); Sat, 31 Mar 2012 17:27:13 -0400 Date: Sat, 31 Mar 2012 17:27:10 -0400 (EDT) Message-Id: <20120331.172710.540592519617177028.davem@davemloft.net> To: drepper@gmail.com Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: sendmmsg: put_user vs __put_user From: David Miller In-Reply-To: References: <20120330.205120.2221145622131588797.davem@davemloft.net> X-Mailer: Mew version 6.4 on Emacs 23.3 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.2.6 (shards.monkeyblade.net [198.137.202.13]); Sat, 31 Mar 2012 14:27:11 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Ulrich Drepper Date: Sat, 31 Mar 2012 08:30:25 -0400 > On Fri, Mar 30, 2012 at 20:51, David Miller wrote: >> Compat processes are not able to generate virtual addresses anywhere >> near the range where the kernel resides, so the address range >> verification done by put_user() is completely superfluous and >> therefore not necessary.  The normal exception handling done by the >> access is completely sufficient. > > I was more thinking about the effects of might_fault() then additional tests. This is very clearly in a context where locks are not held and sleeping would be fine, so I don't see any value in that either.