Subject: Re: [PATCH net-next] net/vxlan: Avoid unaligned access in vxlan_build_skb()

From: Sowmini Varadhan <[email-masked]>
Date: Tue, 20 Sep 2016 11:49:05 -0400

On (09/20/16 08:31), Tom Herbert wrote:
> 
> On Tue, Sep 20, 2016 at 7:27 AM, Sowmini Varadhan
> <[email-masked]> wrote:
> > The vxlan header is at offset (14 + 20 + 8) into the packet,
> > so the vxh is not aligned in vxlan_build_skb. Use [get/put]_unaligned
> > functions to modify flags and vni field in the vxh.
> >
> I'm wondering if VXLAN is just the tip of the iceberg. Wouldn't this
> is also be a problem in GRE and Geneve when they encapsulate Ethernet?
> What about the outer IP header, wouldn't that potentially have
> unaligned accesses also when creating it?

Indeed. All of the above are true, and we have to conquer
each unaligned access, one at a time.

There's also the over-arching problem of arbitrary encapsulations
introducing intervening headers that throw off alignment. 
That would be a design discussion to be had with the ietf.

--Sowmini