kernel: backport fix for initializing skb->cb in the bridge code to 5.4

Fixes issues with proxyarp

Signed-off-by: Felix Fietkau <[email protected]>

target/linux/generic/backport-5.4/610-v5.9-net-bridge-clear-bridge-s-private-skb-space-on-xmit.patch

@@ -0,0 +1,28 @@
+From: Nikolay Aleksandrov <[email protected]>
+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 <[email protected]>
+Signed-off-by: David S. Miller <[email protected]>
+---
+
+--- 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 *
+ 	struct ethhdr *eth;
+ 	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)) {

target/linux/generic/pending-5.4/643-net-bridge-support-hardware-flow-table-offload.patch

@@ -20,7 +20,7 @@ Signed-off-by: Felix Fietkau <[email protected]>
  
  #include <linux/uaccess.h>
  #include "br_private.h"
-@@ -382,6 +386,28 @@ static const struct ethtool_ops br_ethto
+@@ -384,6 +388,28 @@ static const struct ethtool_ops br_ethto
  	.get_link	= ethtool_op_get_link,
  };
  
@@ -49,7 +49,7 @@ Signed-off-by: Felix Fietkau <[email protected]>
  static const struct net_device_ops br_netdev_ops = {
  	.ndo_open		 = br_dev_open,
  	.ndo_stop		 = br_dev_stop,
-@@ -410,6 +436,9 @@ static const struct net_device_ops br_ne
+@@ -412,6 +438,9 @@ static const struct net_device_ops br_ne
  	.ndo_bridge_setlink	 = br_setlink,
  	.ndo_bridge_dellink	 = br_dellink,
  	.ndo_features_check	 = passthru_features_check,