net: bridge: fix multicast-to-unicast with fraglist GSO

Calling skb_copy on a SKB_GSO_FRAGLIST skb is not valid, since it returns
an invalid linearized skb. This code only needs to change the ethernet
header, so pskb_copy is the right function to call here.

Fixes: 6db6f0ea ("bridge: multicast to unicast")
Signed-off-by: Felix Fietkau <nbd@nbd.name>
Acked-by: Paolo Abeni <pabeni@redhat.com>
Acked-by: Nikolay Aleksandrov <razor@blackwall.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/bridge/br_forward.c

@@ -266,7 +266,7 @@ static void maybe_deliver_addr(struct net_bridge_port *p, struct sk_buff *skb,
 	if (skb->dev == p->dev && ether_addr_equal(src, addr))
 		return;
 
-	skb = skb_copy(skb, GFP_ATOMIC);
+	skb = pskb_copy(skb, GFP_ATOMIC);
 	if (!skb) {
 		DEV_STATS_INC(dev, tx_dropped);
 		return;