From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jesper Juhl Subject: [PATCH 6/6][RESEND] Avoid possible NULL pointer deref in 3c359 driver Date: Mon, 13 Aug 2007 00:22:53 +0200 Message-ID: <200708130022.53998.jesper.juhl@gmail.com> References: <200708130016.11281.jesper.juhl@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Cc: Linux Kernel Mailing List , Mike Phillips , netdev@vger.kernel.org, linux-tr@linuxtr.net, davem@davemloft.net, Jesper Juhl To: Andrew Morton Return-path: Received: from ug-out-1314.google.com ([66.249.92.174]:43967 "EHLO ug-out-1314.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759763AbXHLWZT (ORCPT ); Sun, 12 Aug 2007 18:25:19 -0400 Received: by ug-out-1314.google.com with SMTP id j3so542238ugf for ; Sun, 12 Aug 2007 15:25:18 -0700 (PDT) In-Reply-To: <200708130016.11281.jesper.juhl@gmail.com> Content-Disposition: inline Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org (Resending old patch originally submitted at 1/7-2007 02:19, 04-Aug-2007 20:31) In xl_freemem(), if dev_if is NULL, the line struct xl_private *xl_priv =(struct xl_private *)dev->priv; will cause a NULL pointer dereference. However, if we move that assignment below the 'if' statement that tests for a NULL 'dev', then that NULL deref can never happen. It never hurts to be safe :-) Signed-off-by: Jesper Juhl --- diff --git a/drivers/net/tokenring/3c359.c b/drivers/net/tokenring/3c359.c index e22a3f5..671f4da 100644 --- a/drivers/net/tokenring/3c359.c +++ b/drivers/net/tokenring/3c359.c @@ -1044,15 +1044,17 @@ static void xl_freemem(struct net_device *dev) static irqreturn_t xl_interrupt(int irq, void *dev_id) { struct net_device *dev = (struct net_device *)dev_id; - struct xl_private *xl_priv =(struct xl_private *)dev->priv; - u8 __iomem * xl_mmio = xl_priv->xl_mmio ; - u16 intstatus, macstatus ; + struct xl_private *xl_priv; + u8 __iomem * xl_mmio; + u16 intstatus, macstatus; if (!dev) { - printk(KERN_WARNING "Device structure dead, aaahhhh !\n") ; + printk(KERN_WARNING "3c359: Device structure dead, aaahhhh!\n"); return IRQ_NONE; } + xl_priv = (struct xl_private *)dev->priv; + xl_mmio = xl_priv->xl_mmio; intstatus = readw(xl_mmio + MMIO_INTSTATUS) ; if (!(intstatus & 1)) /* We didn't generate the interrupt */