netdev - Re: [PATCH net-next] skbuff: re-add check for NULL skb->head in kfree

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Message-Id: <20170724.162805.1216261982332186633.davem@davemloft.net>
Date:   Mon, 24 Jul 2017 16:28:05 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     fw@...len.de
Cc:     netdev@...r.kernel.org
Subject: Re: [PATCH net-next] skbuff: re-add check for NULL skb->head in
 kfree_skb path

From: Florian Westphal <fw@...len.de>
Date: Sun, 23 Jul 2017 19:54:47 +0200

> A null check is needed after all.  netlink skbs can have skb->head be
> backed by vmalloc.  The netlink destructor vfree()s head, then sets it to
> NULL.  We then panic in skb_release_data with a NULL dereference.
> 
> Re-add such a test.
> 
> Alternative would be to switch to kvfree to free skb->head memory
> and remove the special handling in netlink destructor.
> 
> Reported-by: kernel test robot <fengguang.wu@...el.com>
> Fixes: 06dc75ab06943 ("net: Revert "net: add function to allocate sk_buff head without data area")
> Signed-off-by: Florian Westphal <fw@...len.de>

Ok, back it goes.

Applied, thanks.