From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932666AbcKILE1 (ORCPT ); Wed, 9 Nov 2016 06:04:27 -0500 Received: from mx2.suse.de ([195.135.220.15]:56432 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932557AbcKILEU (ORCPT ); Wed, 9 Nov 2016 06:04:20 -0500 Message-ID: <1478689111.2428.6.camel@suse.com> Subject: Re: [PATCH] USB: serial: fix invalid user-pointer checks From: Oliver Neukum To: Johan Hovold Cc: linux-kernel@vger.kernel.org, linux-usb@vger.kernel.org Date: Wed, 09 Nov 2016 11:58:31 +0100 In-Reply-To: <20161108154117.GN2664@localhost> References: <1478608010-23588-1-git-send-email-johan@kernel.org> <1478614393.2168.2.camel@suse.com> <20161108154117.GN2664@localhost> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.12.11 Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2016-11-08 at 16:41 +0100, Johan Hovold wrote: > On Tue, Nov 08, 2016 at 03:13:13PM +0100, Oliver Neukum wrote: > > On Tue, 2016-11-08 at 13:26 +0100, Johan Hovold wrote: > > > Drop invalid user-pointer checks from ioctl handlers. > > > > > > A NULL-pointer can be valid in user space and copy_to_user() takes > > > care > > > of sanity checking. > > > > Shouldn't we bail out early in these cases? > > I don't think it's worth it, and this is also the general pattern for > such ioctls. The added overhead for an error case like this is really > negligible. OK, as you say. Regards Oliver