From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757615AbYELTAo (ORCPT ); Mon, 12 May 2008 15:00:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756527AbYELTAa (ORCPT ); Mon, 12 May 2008 15:00:30 -0400 Received: from mgw2.diku.dk ([130.225.96.92]:33044 "EHLO mgw2.diku.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756301AbYELTA2 (ORCPT ); Mon, 12 May 2008 15:00:28 -0400 Date: Mon, 12 May 2008 21:00:24 +0200 (CEST) From: Julia Lawall To: James Chapman Cc: linux-kernel@vger.kernel.org, kernel-janitors@vger.kernel.org, netdev Subject: Re: [PATCH 6/6] drivers/net/pppol2tp.c: remove null pointer dereference In-Reply-To: <48287A86.1070401@katalix.com> Message-ID: References: <48287A86.1070401@katalix.com> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 12 May 2008, James Chapman wrote: > Adding netdev to CC list. > > Julia Lawall wrote: > > From: Julia Lawall > > > > If session is NULL, it is not possible to access its name field. So I have > > split apart the printing of the error message to drop the printing of the > > name field in this case. > > I suggest add a note in the patch description that this bug will only be hit > if the driver's debug is enabled. I don't understand the above comment. In both the original and the new code, if session is NULL, the first argument to PRINTK is -1 and the second argument is PPPOL2TP_MSG_CONTROL, for which the only definition seems to be the on in include/linux/if_pppol2tp.h, where it has a non-zero value. So the test in the definition of PRINTK is non-zero and the print occurs. Perhaps this is not what is wanted? julia > > This problem was found using the following semantic match > > (http://www.emn.fr/x-info/coccinelle/) > > > > // > > @@ > > expression E, E1; > > identifier f; > > statement S1,S2,S3; > > @@ > > > > * if (E == NULL) > > { > > ... when != if (E == NULL) S1 else S2 > > when != E = E1 > > * E->f > > ... when any > > return ...; > > } > > else S3 > > // > > Perhaps the above text should be in the additional info section of the patch > description? > > Since this is a network driver, can you resubmit the patch to netdev? > > > Signed-off-by: Julia Lawall > > > > --- > > > > diff -u -p a/drivers/net/pppol2tp.c b/drivers/net/pppol2tp.c > > --- linux-2.6/drivers/net/pppol2tp.c 2008-05-09 16:46:57.000000000 +0200 > > +++ linuxcopy/drivers/net/pppol2tp.c 2008-05-12 15:30:52.000000000 +0200 > > @@ -1621,9 +1621,16 @@ out_no_ppp: > > end: > > release_sock(sk); > > > > - if (error != 0) > > - PRINTK(session ? session->debug : -1, PPPOL2TP_MSG_CONTROL, > > KERN_WARNING, > > - "%s: connect failed: %d\n", session->name, error); > > + if (error != 0) { > > + if (session) > > + PRINTK(session->debug, > > + PPPOL2TP_MSG_CONTROL, KERN_WARNING, > > + "%s: connect failed: %d\n", > > + session->name, error); > > + else > > + PRINTK(-1, PPPOL2TP_MSG_CONTROL, KERN_WARNING, > > + "connect failed: %d\n", error); > > + } > > > > return error; > > } > > > > -- > To unsubscribe from this list: send the line "unsubscribe kernel-janitors" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html >