From mboxrd@z Thu Jan 1 00:00:00 1970 From: Alasdair G Kergon Subject: Re: [PATCH 2/6] drivers/md: remove null pointer dereference Date: Wed, 2 Jul 2008 11:54:34 +0100 Message-ID: <20080702105434.GF22522@agk.fab.redhat.com> References: Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: device-mapper development Cc: kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org List-Id: dm-devel.ids On Mon, May 12, 2008 at 03:37:31PM +0200, Julia Lawall wrote: > If pgpath->pg->ps.type is NULL, it is not possible to access its name > field. So I have simply modified the error message to drop the printing of > the name field. > > This problem was found using the following semantic match > (http://www.emn.fr/x-info/coccinelle/) > --- a/drivers/md/dm-mpath.c 2008-04-16 13:27:57.000000000 +0200 > +++ b/drivers/md/dm-mpath.c 2008-05-12 09:19:35.000000000 +0200 > @@ -884,8 +884,7 @@ static int reinstate_path(struct pgpath > goto out; > > if (!pgpath->pg->ps.type) { > - DMWARN("Reinstate path not supported by path selector %s", > - pgpath->pg->ps.type->name); > + DMWARN("Reinstate path not supported by path selector"); > r = -EINVAL; > goto out; > } Thanks for reporting this. A more-sophisticated checker might discover that the test can never fail - see parse_path_selector() - and so the real problem here is that it is the wrong test. The next line is: r = pgpath->pg->ps.type->reinstate_path(&pgpath->pg->ps, &pgpath->path); and the error message makes it clear that the intent was to ensure that the reinstate_path method exists before attempting to use it. IOW if (!pgpath->pg->ps.type->reinstate_path) { Alasdair -- agk@redhat.com