From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756923AbYKUXzT (ORCPT ); Fri, 21 Nov 2008 18:55:19 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753299AbYKUXzG (ORCPT ); Fri, 21 Nov 2008 18:55:06 -0500 Received: from smtp1.linux-foundation.org ([140.211.169.13]:54452 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752888AbYKUXzE (ORCPT ); Fri, 21 Nov 2008 18:55:04 -0500 Date: Fri, 21 Nov 2008 15:54:21 -0800 From: Andrew Morton To: Pavel Machek Cc: rpurdie@rpsys.net, linux-kernel@vger.kernel.org Subject: Re: backlight: catch invalid input Message-Id: <20081121155421.152cc555.akpm@linux-foundation.org> In-Reply-To: <20081121111414.GA1455@elf.ucw.cz> References: <20081121111414.GA1455@elf.ucw.cz> X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.20; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 21 Nov 2008 12:14:14 +0100 Pavel Machek wrote: > > Currently, echo > brightness turns brightness to zero due to > insufficient checking. Add a test to catch that. > OK. And what happens if you do echo wibble > brightness ? > > diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c > index fab0bc8..5c2e23d 100644 > --- a/drivers/video/backlight/backlight.c > +++ b/drivers/video/backlight/backlight.c > @@ -86,6 +86,8 @@ static ssize_t backlight_store_power(str > int power = simple_strtoul(buf, &endp, 0); > size_t size = endp - buf; > > + if (!size) > + return -EINVAL; > if (*endp && isspace(*endp)) > size++; > if (size != count) A better fix would be to use strict_strtoul() and check its return value.