ipq807x: backport the skb->cb fix from upstream

This was causing sporadic proxy_arp failures.

Fixes: WIFI-7154
Signed-off-by: John Crispin <john@phrozen.org>

feeds/ipq807x/ipq807x/patches/109-net-bridge-clear-bridge-s-private-skb-space-on-xmit.patch

@@ -0,0 +1,36 @@
+From fd65e5a95d08389444e8591a20538b3edece0e15 Mon Sep 17 00:00:00 2001
+From: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
+Date: Fri, 31 Jul 2020 19:26:16 +0300
+Subject: [PATCH] net: bridge: clear bridge's private skb space on xmit
+
+We need to clear all of the bridge private skb variables as they can be
+stale due to the packet being recirculated through the stack and then
+transmitted through the bridge device. Similar memset is already done on
+bridge's input. We've seen cases where proxyarp_replied was 1 on routed
+multicast packets transmitted through the bridge to ports with neigh
+suppress which were getting dropped. Same thing can in theory happen with
+the port isolation bit as well.
+
+Fixes: 821f1b21cabb ("bridge: add new BR_NEIGH_SUPPRESS port flag to suppress arp and nd flood")
+Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+---
+ net/bridge/br_device.c | 2 ++
+ 1 file changed, 2 insertions(+)
+
+diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
+index 8c7b78f8bc23..9a2fb4aa1a10 100644
+--- a/net/bridge/br_device.c
++++ b/net/bridge/br_device.c
+@@ -36,6 +36,8 @@ netdev_tx_t br_dev_xmit(struct sk_buff *skb, struct net_device *dev)
+ 	const unsigned char *dest;
+ 	u16 vid = 0;
+ 
++	memset(skb->cb, 0, sizeof(struct br_input_skb_cb));
++
+ 	rcu_read_lock();
+ 	nf_ops = rcu_dereference(nf_br_ops);
+ 	if (nf_ops && nf_ops->br_dev_xmit_hook(skb)) {
+-- 
+2.25.1
+