netdev - [PATCH] netpoll: don't dereference NULL dev from np

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Message-ID: <4A07FFB3.70308@openvz.org>
Date:	Mon, 11 May 2009 14:36:35 +0400
From:	Pavel Emelyanov <xemul@...nvz.org>
To:	David Miller <davem@...emloft.net>
CC:	Stephen Hemminger <shemminger@...ux-foundation.org>,
	Linux Netdev List <netdev@...r.kernel.org>
Subject: [PATCH] netpoll: don't dereference NULL dev from np

It looks like the dev in netpoll_poll can be NULL - at lease it's 
checked at the function beginning. Thus the dev->netde_ops dereference 
looks dangerous.

Signed-off-by: Pavel Emelyanov <xemul@...nvz.org>

---

diff --git a/net/core/netpoll.c b/net/core/netpoll.c
index b5873bd..64f51ee 100644
--- a/net/core/netpoll.c
+++ b/net/core/netpoll.c
@@ -175,9 +175,13 @@ static void service_arp_queue(struct netpoll_info *npi)
 void netpoll_poll(struct netpoll *np)
 {
 	struct net_device *dev = np->dev;
-	const struct net_device_ops *ops = dev->netdev_ops;
+	const struct net_device_ops *ops;
+
+	if (!dev || !netif_running(dev))
+		return;
 
-	if (!dev || !netif_running(dev) || !ops->ndo_poll_controller)
+	ops = dev->netdev_ops;
+	if (!ops->ndo_poll_controller)
 		return;
 
 	/* Process pending work on NIC */
--
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