Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759543Ab2EIOYm (ORCPT ); Wed, 9 May 2012 10:24:42 -0400 Received: from mail-pb0-f46.google.com ([209.85.160.46]:41237 "EHLO mail-pb0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758108Ab2EIOYl (ORCPT ); Wed, 9 May 2012 10:24:41 -0400 Date: Wed, 9 May 2012 07:24:36 -0700 From: "gregkh@linuxfoundation.org" To: Ian Abbott Cc: H Hartley Sweeten , "devel@driverdev.osuosl.org" , "fmhess@users.sourceforge.net" , Ian Abbott , Linux Kernel Subject: Re: [PATCH] staging: comedi: remove __user annotation inside of struct's Message-ID: <20120509142436.GC11695@kroah.com> References: <201205081641.00358.hartleys@visionengravers.com> <4FAA44D7.1040209@mev.co.uk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4FAA44D7.1040209@mev.co.uk> 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: 2092 Lines: 53 On Wed, May 09, 2012 at 11:20:07AM +0100, Ian Abbott wrote: > 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. When the kernel exports .h files, stuff like this should work "automatically", so there is no need to not put __user markings. So please, yes, continue to work to get this correct, it is very essencial to ensure we don't mess stuff up. thanks, greg k-h -- 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/