net: hsr: validate address B before copying to skb

Validate MAC address before copying the same to outgoing frame
skb destination address. Since a node can have zero mac
address for Link B until a valid frame is received over
that link, this fix address the issue of a zero MAC address
being in the packet.
Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/hsr/hsr_framereg.c

@@ -325,6 +325,7 @@ void hsr_addr_subst_dest(struct hsr_node *node_src, struct sk_buff *skb,
 	if (port->type != node_dst->addr_B_port)
 		return;
 
+	if (is_valid_ether_addr(node_dst->macaddress_B))
 		ether_addr_copy(eth_hdr(skb)->h_dest, node_dst->macaddress_B);
 }