From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759339AbXG2Fwp (ORCPT ); Sun, 29 Jul 2007 01:52:45 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755582AbXG2Fwe (ORCPT ); Sun, 29 Jul 2007 01:52:34 -0400 Received: from pentafluge.infradead.org ([213.146.154.40]:35349 "EHLO pentafluge.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755559AbXG2Fwd (ORCPT ); Sun, 29 Jul 2007 01:52:33 -0400 Date: Sun, 29 Jul 2007 11:34:47 +0530 (IST) From: Satyam Sharma X-X-Sender: satyam@enigma.security.iitk.ac.in To: Domen Puncer cc: Jesper Juhl , Linux Kernel Mailing List , netdev@vger.kernel.org, Steven Hirsch , "David S. Miller" , Franco Venturi Subject: Re: [PATCH] sb1000: prevent a potential NULL pointer dereference in sb1000_dev_ioctl() In-Reply-To: <20070729043707.GA8343@nd47.coderock.org> Message-ID: References: <200707290002.42722.jesper.juhl@gmail.com> <20070729043707.GA8343@nd47.coderock.org> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 29 Jul 2007, Domen Puncer wrote: > On 29/07/07 00:02 +0200, Jesper Juhl wrote: > > Hi, > > > > Here's a small patch, prompted by a find by the Coverity checker, > > that removes a potential NULL pointer dereference from > > drivers/net/sb1000.c::sb1000_dev_ioctl(). > > The checker spotted that we do a NULL test of 'dev', yet we > > dereference the pointer prior to that check. > > This patch simply moves the dereference after the NULL test. > > But... it can't be called without a valid 'dev', no? > A quick 'grep do_ioctl net/' confirms that all calls are in > the form of 'dev->do_ioctl(dev, ...'. Yup, I think so too ... > > @@ -991,11 +991,13 @@ static int sb1000_dev_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd) > > short PID[4]; > > int ioaddr[2], status, frequency; > > unsigned int stats[5]; > > - struct sb1000_private *lp = netdev_priv(dev); > > + struct sb1000_private *lp; > > > > if (!(dev && dev->flags & IFF_UP)) > > return -ENODEV; I think we could get rid of the !dev check itself. Actually, the IFF_UP check /also/ looks suspect to me for two reasons: (1) I remember Stephen Hemminger once telling me dev->flags is legacy and unsafe, and one of the netif_xxx() functions be used instead, and, (2) I wonder if we really require the interface to be up and *running* when we do this ioctl. Satyam