netdev - Re: [PATCH] ipv6: udp packets following an UFO enqueued packet need also be handled by UFO

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Date:	Wed, 2 Oct 2013 13:20:52 +0200
From:	Jiri Pirko <jiri@...nulli.us>
To:	netdev@...r.kernel.org
Cc:	yoshfuji@...ux-ipv6.org, davem@...emloft.net, kuznet@....inr.ac.ru,
	jmorris@...ei.org, kaber@...sh.net, herbert@...dor.apana.org.au,
	eric.dumazet@...il.com, hannes@...essinduktion.org
Subject: Re: [PATCH] ipv6: udp packets following an UFO enqueued packet need
 also be handled by UFO

Wed, Oct 02, 2013 at 01:25:34AM CEST, hannes@...essinduktion.org wrote:
>On Tue, Oct 01, 2013 at 11:47:21PM +0200, Hannes Frederic Sowa wrote:
>> The strange thing is that if I don't do the IPV6_MTU setsockopt I don't
>> get an oops.
>
>This is incorrect, it just depends on the size of the writes and on the
>interface mtu.
>
>> IPv4 seems to work without problems, too.
>
>I also get kernel oopses from IPv4 now, too.

This patch should fix this on ipv4 as well:

Subject: ip_output: do skb ufo init for peeked non ufo skb as well

Now, if user application does:
sendto len<mtu flag MSG_MORE
sendto len>mtu flag 0
The skb is not treated as fragmented one because it is not initialized
that way. So move the initialization to fix this.

Signed-off-by: Jiri Pirko <jiri@...nulli.us>
---
 net/ipv4/ip_output.c | 14 +++++++++-----
 1 file changed, 9 insertions(+), 5 deletions(-)

diff --git a/net/ipv4/ip_output.c b/net/ipv4/ip_output.c
index a04d872..bd21c5d 100644
--- a/net/ipv4/ip_output.c
+++ b/net/ipv4/ip_output.c
@@ -772,15 +772,19 @@ static inline int ip_ufo_append_data(struct sock *sk,
 		/* initialize protocol header pointer */
 		skb->transport_header = skb->network_header + fragheaderlen;
 
-		skb->ip_summed = CHECKSUM_PARTIAL;
 		skb->csum = 0;
 
-		/* specify the length of each IP datagram fragment */
-		skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen;
-		skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
+
 		__skb_queue_tail(queue, skb);
-	}
+	} else if (skb_is_gso(skb))
+		goto append;
+
+	skb->ip_summed = CHECKSUM_PARTIAL;
+	/* specify the length of each IP datagram fragment */
+	skb_shinfo(skb)->gso_size = maxfraglen - fragheaderlen;
+	skb_shinfo(skb)->gso_type = SKB_GSO_UDP;
 
+append:
 	return skb_append_datato_frags(sk, skb, getfrag, from,
 				       (length - transhdrlen));
 }
-- 
1.8.3.1


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