From: Sowmini Varadhan <sowmini.varadhan@oracle.com>
To: Jiri Benc <jbenc@redhat.com>
Cc: netdev@vger.kernel.org, davem@davemloft.net,
hannes@stressinduktion.org, aduyck@mirantis.com,
daniel@iogearbox.net, pabeni@redhat.com
Subject: Re: [PATCH net-next] net/vxlan: Avoid unaligned access in vxlan_build_skb()
Date: Tue, 20 Sep 2016 13:07:42 -0400 [thread overview]
Message-ID: <20160920170742.GR8920@oracle.com> (raw)
In-Reply-To: <20160920184333.17444823@griffin>
On (09/20/16 18:43), Jiri Benc wrote:
>
> IPv6 header is certainly not 20 bytes.
vxlan encapsulates an IPv6/ethernet frame in a UDP/IPv4/ethernet packet.
the ipv4 header is 20 bytes (without options).
mld_newpack is dealing with the vxlan net_device in this case,
which has ->hard_header_len of 14, and ->needed_headroom of 64,
so hlen (used in mld_newpack) comes out to be 80.
> If you see unaligned access, something is wrong. But I very much doubt
> that the problem is at the place you're trying to fix. Could you share
> the traces with us?
Exactly what traces do you want? I think you can check this easily
by using printk's predicated on IS_ALIGNED checks in vxlan_build_skb().
IPv6 MLD triggers this quite easily.
I will try out Hannes' solution (which makes sense) in a moment,
and report back.
--Sowmini
next prev parent reply other threads:[~2016-09-20 17:08 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-20 14:27 [PATCH net-next] net/vxlan: Avoid unaligned access in vxlan_build_skb() Sowmini Varadhan
2016-09-20 15:31 ` Tom Herbert
2016-09-20 15:49 ` Sowmini Varadhan
2016-09-20 16:11 ` Jiri Benc
2016-09-20 16:31 ` Sowmini Varadhan
2016-09-20 16:43 ` Jiri Benc
2016-09-20 17:07 ` Sowmini Varadhan [this message]
2016-09-20 17:15 ` Jiri Benc
2016-09-20 17:09 ` Jiri Benc
2016-09-20 17:19 ` Tom Herbert
2016-09-20 17:24 ` Sowmini Varadhan
2016-09-22 5:52 ` David Miller
2016-09-22 21:30 ` Sowmini Varadhan
2016-09-23 12:06 ` David Miller
2016-09-23 14:17 ` Alexander Duyck
2016-09-23 17:20 ` Sowmini Varadhan
2016-09-23 17:38 ` Alexander Duyck
2016-09-23 23:41 ` Sowmini Varadhan
2016-09-24 0:43 ` Alexander Duyck
2016-09-28 17:03 ` Sowmini Varadhan
2016-09-28 18:08 ` Alexander Duyck
2016-09-28 19:56 ` Sowmini Varadhan
2016-09-20 16:45 ` Hannes Frederic Sowa
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