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>

diff --git a/net/bridge/br_device.c b/net/bridge/br_device.c
index 8c7b78f8bc230f5811803f83ab72ee42b71be5e2..9a2fb4aa1a10e186e62a905429d7216a2ec20c0e 100644 (file)
--- 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)) {