Patch "net: core: don't account for udp header size when computing seglen" has been added to the 3.10-stable tree

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This is a note to let you know that I've just added the patch titled

    net: core: don't account for udp header size when computing seglen

to the 3.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     net-core-don-t-account-for-udp-header-size-when-computing-seglen.patch
and it can be found in the queue-3.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.


>From foo@baz Wed May 28 20:43:09 PDT 2014
From: Florian Westphal <fw@xxxxxxxxx>
Date: Wed, 9 Apr 2014 10:28:50 +0200
Subject: net: core: don't account for udp header size when computing seglen

From: Florian Westphal <fw@xxxxxxxxx>

[ Upstream commit 6d39d589bb76ee8a1c6cde6822006ae0053decff ]

In case of tcp, gso_size contains the tcpmss.

For UFO (udp fragmentation offloading) skbs, gso_size is the fragment
payload size, i.e. we must not account for udp header size.

Otherwise, when using virtio drivers, a to-be-forwarded UFO GSO packet
will be needlessly fragmented in the forward path, because we think its
individual segments are too large for the outgoing link.

Fixes: fe6cc55f3a9a053 ("net: ip, ipv6: handle gso skbs in forwarding path")
Cc: Eric Dumazet <eric.dumazet@xxxxxxxxx>
Reported-by: Tobias Brunner <tobias@xxxxxxxxxxxxxx>
Signed-off-by: Florian Westphal <fw@xxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 net/core/skbuff.c |   12 +++++++-----
 1 file changed, 7 insertions(+), 5 deletions(-)

--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -3487,12 +3487,14 @@ EXPORT_SYMBOL(skb_try_coalesce);
 unsigned int skb_gso_transport_seglen(const struct sk_buff *skb)
 {
 	const struct skb_shared_info *shinfo = skb_shinfo(skb);
-	unsigned int hdr_len;
 
 	if (likely(shinfo->gso_type & (SKB_GSO_TCPV4 | SKB_GSO_TCPV6)))
-		hdr_len = tcp_hdrlen(skb);
-	else
-		hdr_len = sizeof(struct udphdr);
-	return hdr_len + shinfo->gso_size;
+		return tcp_hdrlen(skb) + shinfo->gso_size;
+
+	/* UFO sets gso_size to the size of the fragmentation
+	 * payload, i.e. the size of the L4 (UDP) header is already
+	 * accounted for.
+	 */
+	return shinfo->gso_size;
 }
 EXPORT_SYMBOL_GPL(skb_gso_transport_seglen);


Patches currently in stable-queue which might be from fw@xxxxxxxxx are

queue-3.10/netfilter-can-t-fail-and-free-after-table-replacement.patch
queue-3.10/net-core-don-t-account-for-udp-header-size-when-computing-seglen.patch
queue-3.10/net-ipv6-send-pkttoobig-immediately-if-orig-frag-size-mtu.patch
queue-3.10/net-ipv4-ip_forward-fix-inverted-local_df-test.patch
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