netdev - Re: [PATCH net] udp: consistently apply ufo or fragmentation

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Message-Id: <20170810.095226.1892134367440824522.davem@davemloft.net>
Date:   Thu, 10 Aug 2017 09:52:26 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     willemdebruijn.kernel@...il.com
Cc:     netdev@...r.kernel.org, andreyknvl@...il.com, willemb@...gle.com
Subject: Re: [PATCH net] udp: consistently apply ufo or fragmentation

From: Willem de Bruijn <willemdebruijn.kernel@...il.com>
Date: Thu, 10 Aug 2017 12:29:19 -0400

> From: Willem de Bruijn <willemb@...gle.com>
> 
> When iteratively building a UDP datagram with MSG_MORE and that
> datagram exceeds MTU, consistently choose UFO or fragmentation.
> 
> Once skb_is_gso, always apply ufo. Conversely, once a datagram is
> split across multiple skbs, do not consider ufo.
> 
> Sendpage already maintains the first invariant, only add the second.
> IPv6 does not have a sendpage implementation to modify.
> 
> A gso skb must have a partial checksum, do not follow sk_no_check_tx
> in udp_send_skb.
> 
> Found by syzkaller.
> 
> Fixes: e89e9cf539a2 ("[IPv4/IPv6]: UFO Scatter-gather approach")
> Reported-by: Andrey Konovalov <andreyknvl@...gle.com>
> Signed-off-by: Willem de Bruijn <willemb@...gle.com>

Applied and queued up for -stable.