Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752559AbaG0SVE (ORCPT ); Sun, 27 Jul 2014 14:21:04 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:40101 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752207AbaG0SVB (ORCPT ); Sun, 27 Jul 2014 14:21:01 -0400 Date: Sun, 27 Jul 2014 11:21:01 -0700 From: Greg Kroah-Hartman To: Malcolm Priestley Cc: Guillaume =?iso-8859-1?Q?CL=C9MENT?= , devel@driverdev.osuosl.org, Forest Bond , Dan Carpenter , linux-kernel@vger.kernel.org Subject: Re: [PATCH] staging: vt6655: fix direct dereferencing of user pointer Message-ID: <20140727182101.GA11593@kroah.com> References: <20140725123301.GZ13737@mwanda> <1406292443-11734-1-git-send-email-gclement@baobob.org> <53D2E3BD.1000208@gmail.com> <20140726082429.GA3121@pleinair.baobob.org> <20140726091843.GA5956@pleinair.baobob.org> <53D386A9.9040001@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <53D386A9.9040001@gmail.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, Jul 26, 2014 at 11:44:57AM +0100, Malcolm Priestley wrote: > On 26/07/14 10:18, Guillaume CL?MENT wrote: > >On Sat, Jul 26, 2014 at 10:24:30AM +0200, Guillaume CL?MENT wrote: > >>Hi Malcolm, > >> > >>On Sat, Jul 26, 2014 at 12:09:49AM +0100, Malcolm Priestley wrote: > >>>Hi Guillaume > >>> > >>>On 25/07/14 13:47, Guillaume Clement wrote: > >>>>Sparse reported that the data from tagSCmdRequest is given by > >>>>userspace, so it should be tagged as such. > >>>extra is not in user space > >>> > >> > >>All right. > >> > >>This is still confusing to me because, taking the SIOCSIWGENIE ioctl as > >>an example, in device_main.c, we have this code: > >> > >>rc = iwctl_siwgenie(dev, NULL, &(wrq->u.data), wrq->u.data.pointer); > >> > >>Here the extra parameter is the last one, wrq->u.data.pointer. > >> > >>I was led to believe that wrq->u.data.pointer is in userspace (this was > >>reported by sparse actually) because the pointer field in data is > >>actually defined as __user. > >> > >> > >By the way, the original code (before my patch) reads: > > > > if ((wrq->length < 2) || (extra[1]+2 != wrq->length)) { > > ret = -EINVAL; > > goto out; > > } > > if (wrq->length > MAX_WPA_IE_LEN) { > > ret = -ENOMEM; > > goto out; > > } > > memset(pMgmt->abyWPAIE, 0, MAX_WPA_IE_LEN); > > if (copy_from_user(pMgmt->abyWPAIE, extra, wrq->length)) { > > ret = -EFAULT; > > goto out; > > } > > > >Note extra[1] and later copy_from_user(x, extra, y). > > > >If extra is not in userspace, we should not call copy_from_user, and if > >it is, we should not dereference it. There is definitely something fishy > >here. > > > > I got it wrong when the iw_handler is not present a standard ioctl is called > extra is in userspace. > > Sorry for the noise. So this patch is acceptable? confused, 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/