From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751771AbWEEUod (ORCPT ); Fri, 5 May 2006 16:44:33 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751772AbWEEUod (ORCPT ); Fri, 5 May 2006 16:44:33 -0400 Received: from mx.freeshell.ORG ([192.94.73.18]:26091 "EHLO sdf.lonestar.org") by vger.kernel.org with ESMTP id S1751771AbWEEUod (ORCPT ); Fri, 5 May 2006 16:44:33 -0400 Date: Fri, 5 May 2006 20:44:10 +0000 (UTC) From: Alexey Toptygin To: Andi Kleen cc: linux-kernel@vger.kernel.org, tony.luck@intel.com Subject: Re: [PATCH] sendfile compat functions on x86_64 and ia64 In-Reply-To: <200605052238.26834.ak@suse.de> Message-ID: References: <200605052238.26834.ak@suse.de> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 5 May 2006, Andi Kleen wrote: > With your change there wouldn't be any sign extension and rw_verify_area > couldn't reject negative values them anymore. > > I think it would be a wrong change because it would differ from a native > 32bit kernel. No... On a 32 bit kernel (and on a 64 bit kernel using the native interface), count is passed to sendfile as unsigned. rw_verify_area explicitly casts to signed before checking for negativeness. The only place anywhere in the kernel that count is signed (other than where rw_verify area explicitly casts it for one test) is in the declaration of sys32_sendfile in the x86_64 compat code. I'm pretty sure it's supposed to be unsigned there too, and the current code is a typo. Alexey