linux-kernel - Re: [2.6.33-rc5 regression] NULL pointer dereference in vlan_skb_recv - probably introduced by commit 9793241fe92f7d9303fb221e43fc598eb065f267

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Message-ID: <4B5C74BF.5060604@gmail.com>
Date:	Sun, 24 Jan 2010 17:26:39 +0100
From:	Eric Dumazet <eric.dumazet@...il.com>
To:	Bruno Prémont <bonbons@...ux-vserver.org>
CC:	Eric Dumazet <eric.dumazet@...il.com>,
	"David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [2.6.33-rc5 regression] NULL pointer dereference in vlan_skb_recv
 - probably introduced by commit 9793241fe92f7d9303fb221e43fc598eb065f267

Le 24/01/2010 16:25, Bruno Prémont a écrit :
> 
> In addition to previous mail, I'm also dumping the result of
> vlan_dev_info(dev) shows that the returned pointer is not the same
> during vlan_dev_init() and vlan_skb_recv() ...
> 

> 
> This might explain the NULL rx_stats pointer, but why do there exist
> two distinct vlan_dev_info(dev)? (unless in one case dev would be
> the physical network device and in the other case it would be vlan device?
> that is lan versus lan.658 in my case...)
> 


Ok, I believe I found the problem :)

Please try following patch, if it works I'll submit with appropriate Changelog and signatures

Thanks


diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c
index b788978..c1b92ca 100644
--- a/net/8021q/vlan_dev.c
+++ b/net/8021q/vlan_dev.c
@@ -163,7 +163,7 @@ int vlan_skb_recv(struct sk_buff *skb, struct net_device *dev,
 		goto err_unlock;
 	}
 
-	rx_stats = per_cpu_ptr(vlan_dev_info(dev)->vlan_rx_stats,
+	rx_stats = per_cpu_ptr(vlan_dev_info(skb->dev)->vlan_rx_stats,
 			       smp_processor_id());
 	rx_stats->rx_packets++;
 	rx_stats->rx_bytes += skb->len;
--
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