From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756801Ab1JCQ1M (ORCPT ); Mon, 3 Oct 2011 12:27:12 -0400 Received: from rcsinet15.oracle.com ([148.87.113.117]:25911 "EHLO rcsinet15.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753351Ab1JCQ1H (ORCPT ); Mon, 3 Oct 2011 12:27:07 -0400 Date: Mon, 3 Oct 2011 12:26:44 -0400 From: Konrad Rzeszutek Wilk To: Ian Campbell Cc: "linux-kernel@vger.kernel.org" , "xen-devel@lists.xensource.com" , Dan Carpenter Subject: Re: [Xen-devel] [PATCH 7/9] xen/xenbus: Check before dereferencing it. Message-ID: <20111003162644.GF17108@phenom.oracle.com> References: <1317325971-21603-1-git-send-email-konrad.wilk@oracle.com> <1317325971-21603-8-git-send-email-konrad.wilk@oracle.com> <1317369681.26672.218.camel@zakaz.uk.xensource.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1317369681.26672.218.camel@zakaz.uk.xensource.com> User-Agent: Mutt/1.5.21 (2010-09-15) X-Source-IP: rtcsinet21.oracle.com [66.248.204.29] X-CT-RefId: str=0001.0A090204.4E89E256.009B,ss=1,re=0.000,fgs=0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Sep 30, 2011 at 09:01:21AM +0100, Ian Campbell wrote: > On Thu, 2011-09-29 at 20:52 +0100, Konrad Rzeszutek Wilk wrote: > > . we do the check whether 'xdev' is NULL - but after we have > > dereferenced it. > > > > Signed-off-by: Konrad Rzeszutek Wilk > > --- > > drivers/xen/xenbus/xenbus_probe_backend.c | 3 ++- > > 1 files changed, 2 insertions(+), 1 deletions(-) > > > > diff --git a/drivers/xen/xenbus/xenbus_probe_backend.c b/drivers/xen/xenbus/xenbus_probe_backend.c > > index 60adf91..331589a 100644 > > --- a/drivers/xen/xenbus/xenbus_probe_backend.c > > +++ b/drivers/xen/xenbus/xenbus_probe_backend.c > > @@ -103,10 +103,11 @@ static int xenbus_uevent_backend(struct device *dev, > > return -ENODEV; > > > > xdev = to_xenbus_device(dev); > > to_xenbus_device is just container_of. The only way it would return NULL > is if dev == offsetof(struct xenbus_device, dev), which isn't terribly > likely. A more likely error would be dev == NULL and we just checked > above. > > > - bus = container_of(xdev->dev.bus, struct xen_bus_type, bus); > > if (xdev == NULL) > > return -ENODEV; Hm, in which case this 'xdev == NULL' is pointless. Will remove it.