netdev - Re: [PATCH net] macvtap: always pass ethernet header in linear

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Date:	Fri, 11 Mar 2016 14:45:54 -0500 (EST)
From:	David Miller <davem@...emloft.net>
To:	willemdebruijn.kernel@...il.com
Cc:	netdev@...r.kernel.org, willemb@...gle.com
Subject: Re: [PATCH net] macvtap: always pass ethernet header in linear

From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
Date: Tue,  8 Mar 2016 15:18:54 -0500

> From: Willem de Bruijn <willemb@...gle.com>
> 
> The stack expects link layer headers in the skb linear section.
> Macvtap can create skbs with llheader in frags in edge cases:
> when (IFF_VNET_HDR is off or vnet_hdr.hdr_len < ETH_HLEN) and
> prepad + len > PAGE_SIZE and vnet_hdr.flags has no or bad csum.
> 
> Add checks to ensure linear is always at least ETH_HLEN.
> At this point, len is already ensured to be >= ETH_HLEN.
> 
> For backwards compatiblity, rounds up short vnet_hdr.hdr_len.
> This differs from tap and packet, which return an error.
> 
> Fixes b9fb9ee07e67 ("macvtap: add GSO/csum offload support")
> Signed-off-by: Willem de Bruijn <willemb@...gle.com>

Applied to net-next and queued up for -stable, thanks.