netdev - Re: [PATCH net v2] vlan: pull on __vlan_insert_tag error path and fix csum correction

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Message-Id: <20160415.232049.1582872962762792747.davem@davemloft.net>
Date:	Fri, 15 Apr 2016 23:20:49 -0400 (EDT)
From:	David Miller <davem@...emloft.net>
To:	daniel@...earbox.net
Cc:	jiri@...nulli.us, netdev@...r.kernel.org
Subject: Re: [PATCH net v2] vlan: pull on __vlan_insert_tag error path and
 fix csum correction

From: Daniel Borkmann <daniel@...earbox.net>
Date: Sat, 16 Apr 2016 02:27:58 +0200

> When __vlan_insert_tag() fails from skb_vlan_push() path due to the
> skb_cow_head(), we need to undo the __skb_push() in the error path
> as well that was done earlier to move skb->data pointer to mac header.
> 
> Moreover, I noticed that when in the non-error path the __skb_pull()
> is done and the original offset to mac header was non-zero, we fixup
> from a wrong skb->data offset in the checksum complete processing.
> 
> So the skb_postpush_rcsum() really needs to be done before __skb_pull()
> where skb->data still points to the mac header start and thus operates
> under the same conditions as in __vlan_insert_tag().
> 
> Fixes: 93515d53b133 ("net: move vlan pop/push functions into common code")
> Signed-off-by: Daniel Borkmann <daniel@...earbox.net>
> Reviewed-by: Jiri Pirko <jiri@...lanox.com>
> ---
>  v1 -> v2:
>    - Resend/code still the same, Jiri gave it a review as well meanwhile.

Applied and queued up for -stable, thanks Daniel.