[PATCH 3.16 01/55] netlink: reset network header before passing to taps

From: Greg Kroah-Hartman
Date: Sun Oct 12 2014 - 22:44:59 EST

3.16-stable review patch. If anyone has any objections, please let me know.


From: Daniel Borkmann <dborkman@xxxxxxxxxx>

[ 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@xxxxxxxxxxxx>
Signed-off-by: Daniel Borkmann <dborkman@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
net/netlink/af_netlink.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -205,7 +205,7 @@ static int __netlink_deliver_tap_skb(str
nskb->protocol = htons((u16) sk->sk_protocol);
nskb->pkt_type = netlink_is_kernel(sk) ?
+ skb_reset_network_header(nskb);
ret = dev_queue_xmit(nskb);
if (unlikely(ret > 0))
ret = net_xmit_errno(ret);

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