From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754548Ab0C3QZM (ORCPT ); Tue, 30 Mar 2010 12:25:12 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:56080 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750902Ab0C3QZK (ORCPT ); Tue, 30 Mar 2010 12:25:10 -0400 To: Dan Carpenter Cc: Martin Schwidefsky , Heiko Carstens , linux390@de.ibm.com, Hans-Joachim Picht , Sebastian Ott , linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org Subject: Re: [patch] s390: potential buffer overflow References: <20100330094342.GJ5069@bicker> From: ebiederm@xmission.com (Eric W. Biederman) Date: Tue, 30 Mar 2010 09:25:01 -0700 In-Reply-To: <20100330094342.GJ5069@bicker> (Dan Carpenter's message of "Tue\, 30 Mar 2010 12\:43\:42 +0300") Message-ID: User-Agent: Gnus/5.11 (Gnus v5.11) Emacs/22.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-XM-SPF: eid=;;;mid=;;;hst=in01.mta.xmission.com;;;ip=76.21.114.89;;;frm=ebiederm@xmission.com;;;spf=neutral X-SA-Exim-Connect-IP: 76.21.114.89 X-SA-Exim-Rcpt-To: error27@gmail.com, kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, sebott@linux.vnet.ibm.com, hans@linux.vnet.ibm.com, linux390@de.ibm.com, heiko.carstens@de.ibm.com, schwidefsky@de.ibm.com X-SA-Exim-Mail-From: ebiederm@xmission.com X-SA-Exim-Scanned: No (on in01.mta.xmission.com); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dan Carpenter writes: > "len" hasn't been properly range checked so we shouldn't use it as an > array offset. This can only be written to by root but it would still be > annoying to accidentally write more than 3 characters and corrupt your > memory. > > Signed-off-by: Dan Carpenter > --- > I don't have a cross compile environment to compile this. Sorry. :/ > > diff --git a/drivers/s390/char/sclp_async.c b/drivers/s390/char/sclp_async.c > index f449c69..72c2e90 100644 > --- a/drivers/s390/char/sclp_async.c > +++ b/drivers/s390/char/sclp_async.c > @@ -84,7 +84,7 @@ static int proc_handler_callhome(struct ctl_table *ctl, int write, > rc = copy_from_user(buf, buffer, sizeof(buf)); > if (rc != 0) > return -EFAULT; > - buf[len - 1] = '\0'; > + buf[sizeof(buf) - 1] = '\0'; > if (strict_strtoul(buf, 0, &val) != 0) > return -EINVAL; > if (val != 0 && val != 1) > @@ -99,6 +99,7 @@ static int proc_handler_callhome(struct ctl_table *ctl, int write, > static struct ctl_table callhome_table[] = { > { > .procname = "callhome", > + .maxlen = 3, > .mode = 0644, > .proc_handler = proc_handler_callhome, > }, Setting maxlen won't do any good as proc_handler_callhome doesn't look at it. Eric