netdev - Re: NULL pointer dereference panic in stable (2.6.33.2), amd64

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Date:	Thu, 15 Apr 2010 14:33:21 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	eric.dumazet@...il.com
Cc:	krkumar2@...ibm.com, netdev@...r.kernel.org,
	nuclearcat@...learcat.com
Subject: Re: NULL pointer dereference panic in stable (2.6.33.2), amd64

From: Eric Dumazet <eric.dumazet@...il.com>
Date: Thu, 15 Apr 2010 22:46:15 +0200

> Le jeudi 15 avril 2010 à 22:30 +0200, Eric Dumazet a écrit :
>>  
>> @@ -1938,6 +1928,8 @@ gso:
>>  		if (dev->priv_flags & IFF_XMIT_DST_RELEASE)
>>  			skb_dst_drop(nskb);
>>  
>> +		skb_orphan(nskb);
>> +
>>  		rc = ops->ndo_start_xmit(nskb, dev);
>>  		if (unlikely(rc != NETDEV_TX_OK)) {
>>  			if (rc & ~NETDEV_TX_MASK)
> 
> Well, might need to test if skb is not shared before orphaning it
> 
> 	if (!skb_shared(skb))
> 		skb_orphan(nskb);

If it's not legal to skb_orphan() here then it would not be legal for
the drivers to unconditionally skb_orphan(), which they do.

So either your test is unnecessary, or we have a big existing problem
:-)

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