From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161230AbWJKUVB (ORCPT ); Wed, 11 Oct 2006 16:21:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161229AbWJKUVA (ORCPT ); Wed, 11 Oct 2006 16:21:00 -0400 Received: from havoc.gtf.org ([69.61.125.42]:39380 "EHLO havoc.gtf.org") by vger.kernel.org with ESMTP id S1161193AbWJKUU6 (ORCPT ); Wed, 11 Oct 2006 16:20:58 -0400 Date: Wed, 11 Oct 2006 16:20:53 -0400 From: Jeff Garzik To: kkeil@suse.de, Andrew Morton , LKML Subject: [PATCH] ISDN: fix drivers, by handling errors thrown by ->readstat() Message-ID: <20061011202053.GA9671@havoc.gtf.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org This is a particularly ugly on-failure bug, possibly security, since the lack of error handling here is covering up another class of bug: failure to handle copy_to_user() return values. The I4L API function ->readstat() returns an integer, and by looking at several existing driver implementations, it is clear that a negative return value was meant to indicate an error. Given that several drivers already return a negative value indicating an errno-style error, the current code would blindly accept that [negative] value as a valid amount of bytes read. Obvious damage ensues. Correcting ->readstat() handling to properly notice errors fixes the existing code to work correctly on error, and enables future patches to more easily indicate errors during operation. Signed-off-by: Jeff Garzik --- drivers/isdn/i4l/isdn_common.c | 9 ++++++--- 1 file changed, 6 insertions(+), 3 deletions(-) diff --git a/drivers/isdn/i4l/isdn_common.c b/drivers/isdn/i4l/isdn_common.c index c3d79ee..69aee26 100644 --- a/drivers/isdn/i4l/isdn_common.c +++ b/drivers/isdn/i4l/isdn_common.c @@ -1134,9 +1134,12 @@ isdn_read(struct file *file, char __user if (dev->drv[drvidx]->interface->readstat) { if (count > dev->drv[drvidx]->stavail) count = dev->drv[drvidx]->stavail; - len = dev->drv[drvidx]->interface-> - readstat(buf, count, drvidx, - isdn_minor2chan(minor)); + len = dev->drv[drvidx]->interface->readstat(buf, count, + drvidx, isdn_minor2chan(minor)); + if (len < 0) { + retval = len; + goto out; + } } else { len = 0; }