Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1946650AbWKAGtx (ORCPT ); Wed, 1 Nov 2006 01:49:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1946642AbWKAGtx (ORCPT ); Wed, 1 Nov 2006 01:49:53 -0500 Received: from 1wt.eu ([62.212.114.60]:1541 "EHLO 1wt.eu") by vger.kernel.org with ESMTP id S1946650AbWKAGtx (ORCPT ); Wed, 1 Nov 2006 01:49:53 -0500 Date: Wed, 1 Nov 2006 08:49:22 +0100 From: Willy Tarreau To: Chris Wright Cc: linux-kernel@vger.kernel.org, Jeff Garzik , Karsten Keil Subject: Re: [PATCH 49/61] ISDN: fix drivers, by handling errors thrown by ->readstat() Message-ID: <20061101074922.GE543@1wt.eu> References: <20061101053340.305569000@sous-sol.org> <20061101054422.145185000@sous-sol.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20061101054422.145185000@sous-sol.org> User-Agent: Mutt/1.5.11 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2321 Lines: 60 On Tue, Oct 31, 2006 at 09:34:29PM -0800, Chris Wright wrote: > -stable review patch. If anyone has any objections, please let us know. > ------------------ > > From: Jeff Garzik > > 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 > Cc: Karsten Keil > Cc: > Signed-off-by: Andrew Morton > Signed-off-by: Linus Torvalds > Signed-off-by: Chris Wright > --- > drivers/isdn/i4l/isdn_common.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > --- linux-2.6.18.1.orig/drivers/isdn/i4l/isdn_common.c > +++ linux-2.6.18.1/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; > } Seems appropriate for 2.4 too. Jeff, Karsten, no objection ? Willy - 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/