From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oliver Hartkopp Subject: Re: [PATCH] 3c507.c: remove unused NULL pointer check Date: Mon, 21 Dec 2009 21:46:23 +0100 Message-ID: <4B2FDE9F.1070108@hartkopp.net> References: <200912211923.58735.strakh@ispras.ru> <4B2FA8C7.3010509@hartkopp.net> <20091221123111.4498b17c@nehalam> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: Alexander Strakh , Bartlomiej Zolnierkiewicz , Donald Becker , netdev@vger.kernel.org, linux-kernel@vger.kernel.org To: Stephen Hemminger Return-path: Received: from mo-p00-ob.rzone.de ([81.169.146.162]:43820 "EHLO mo-p00-ob.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757118AbZLUUqY (ORCPT ); Mon, 21 Dec 2009 15:46:24 -0500 In-Reply-To: <20091221123111.4498b17c@nehalam> Sender: netdev-owner@vger.kernel.org List-ID: Stephen Hemminger wrote: > On Mon, 21 Dec 2009 17:56:39 +0100 > Oliver Hartkopp wrote: > >> Alexander Strakh wrote: >>> In driver drivers/net/3c507.c in function Iirqreturn_t el16_interrupt: >>> 1. If in line 555 dev = NULL then we goto line 556 >>> 2. In line 556 we have null dereference because pr_err called with dev->name >>> in third parameter. >>> 555 if (dev == NULL) { >>> 556 pr_err("%s: net_interrupt(): irq %d for unknown device. >>> \n", >>> 557 dev->name, irq); >>> 558 return IRQ_NONE; >>> 559 } >>> >>> Found by Linux Device Drivers Verification (Svace detector) >>> >>> Remove unused NULL pointer check. > > Interrupts will never be called with third parameter of NULL. It is really > bogus impossible to reach code. > You're right! I just did not verify the direct assignment of dev = dev_id ... Btw. the description for the reason of this patch remains unsuitably as the problem is not the potential dereferencing of dev->name in pr_err() here. It should better be something like this (partly stolen from your answer): Interrupts will never be called with dev_id parameter of NULL. This patch removes the obsolete, unreachable code. Regards, Oliver