netdev - Re: [net] net: fix double free issue of skbuff

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Message-Id: <20160229.120154.1521809488996597623.davem@davemloft.net>
Date:	Mon, 29 Feb 2016 12:01:54 -0500 (EST)
From:	David Miller <davem@...emloft.net>
To:	zhangshengju@...s.chinamobile.com
Cc:	netdev@...r.kernel.org
Subject: Re: [net] net: fix double free issue of skbuff

From: Zhang Shengju <zhangshengju@...s.chinamobile.com>
Date: Mon, 29 Feb 2016 12:22:53 +0000

> If skb_reorder_vlan_header() failed, skb is freed and NULL is returned.
> Then at skb_vlan_untag(), it will free skbuff again which cause double
> free.

The 'skb' local variable in this case will be set to "NULL", calling
kfree_skb() on NULL doesn't do anything.

> This patch removes kfree_skb() call in function skb_reorder_vlan_header().
> 
> Signed-off-by: Zhang Shengju <zhangshengju@...s.chinamobile.com>

Please analyze the complete control path of the caller of this
function, and you'll find that everything is fine.