Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752039Ab2EIKUP (ORCPT ); Wed, 9 May 2012 06:20:15 -0400 Received: from mail.mev.co.uk ([62.49.15.74]:49547 "EHLO mail.mev.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750829Ab2EIKUN (ORCPT ); Wed, 9 May 2012 06:20:13 -0400 Message-ID: <4FAA44D7.1040209@mev.co.uk> Date: Wed, 9 May 2012 11:20:07 +0100 From: Ian Abbott User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:11.0) Gecko/20120414 Thunderbird/11.0.1 MIME-Version: 1.0 To: H Hartley Sweeten CC: Linux Kernel , "devel@driverdev.osuosl.org" , "fmhess@users.sourceforge.net" , Ian Abbott , "gregkh@linuxfoundation.org" Subject: Re: [PATCH] staging: comedi: remove __user annotation inside of struct's References: <201205081641.00358.hartleys@visionengravers.com> In-Reply-To: Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1867 Lines: 45 On 2012-05-09 00:55, H Hartley Sweeten wrote: > On Tuesday, May 08, 2012 4:41 PM, H Hartley Sweeten wrote: >> >> The structs' comedi_insn, coomedi_insnlist, comedi_cmd, >> comedi_chaninfo, and comedi_rangeinfo are all passed to >> the kernel from user space using ioctl commands. They >> are then copied to kernel space using copy_from_user() >> before the data is passed to the drivers. >> >> The __user annotation should not be used with variables >> inside the struct. This produces a lot of sparse warnings >> like: >> >> warning: dereference of noderef expression >> >> Signed-off-by: H Hartley Sweeten >> Cc: Ian Abbott >> Cc: Mori Hess >> Cc: Greg Kroah-Hartman >> >> --- >> >> Note: This patch exposes some new warnings about different >> address space. These will be addressed. > > Please ignore this patch. > > It appears the annotations in the struct definitions are correct. Personally, I think you were on the mark with the patch. It's better to avoid using __user in comedi.h so it can be used as-is in user-space. All of the structures in comedi.h are used in user-space (although Comedilib uses its own version of comedi.h without all the typedef eliminations that have been done in "staging") and some of them are also deep-copied into kernel-space objects of the same type, where the pointers in the structs would no longer be user-space pointers. -- -=( Ian Abbott @ MEV Ltd. E-mail: )=- -=( Tel: +44 (0)161 477 1898 FAX: +44 (0)161 718 3587 )=- -- 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/