[3.13.y.z extended stable] Patch "netlink: reset network header before passing to taps" has been added to staging queue

Kamal Mostafa kamal at canonical.com
Fri Oct 31 20:53:18 UTC 2014

This is a note to let you know that I have just added a patch titled

    netlink: reset network header before passing to taps

to the linux-3.13.y-queue branch of the 3.13.y.z extended stable tree 
which can be found at:


This patch is scheduled to be released in version

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.13.y.z tree, see



>From 18c2c1df45cb7e8ef5bf094379eda6361dc20ca6 Mon Sep 17 00:00:00 2001
From: Daniel Borkmann <dborkman at redhat.com>
Date: Thu, 7 Aug 2014 22:22:47 +0200
Subject: netlink: reset network header before passing to taps

[ Upstream commit 4e48ed883c72e78c5a910f8831ffe90c9b18f0ec ]

netlink doesn't set any network header offset thus when the skb is
being passed to tap devices via dev_queue_xmit_nit(), it emits klog
false positives due to it being unset like:

  [  124.990397] protocol 0000 is buggy, dev nlmon0
  [  124.990411] protocol 0000 is buggy, dev nlmon0

So just reset the network header before passing to the device; for
packet sockets that just means nothing will change - mac and net
offset hold the same value just as before.

Reported-by: Marcel Holtmann <marcel at holtmann.org>
Signed-off-by: Daniel Borkmann <dborkman at redhat.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
 net/netlink/af_netlink.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index dbba678..cb5b7e0 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -204,7 +204,7 @@ static int __netlink_deliver_tap_skb(struct sk_buff *skb,
 	if (nskb) {
 		nskb->dev = dev;
 		nskb->protocol = htons((u16) sk->sk_protocol);
+		skb_reset_network_header(nskb);
 		ret = dev_queue_xmit(nskb);
 		if (unlikely(ret > 0))
 			ret = net_xmit_errno(ret);

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