net: bridge: stp: don't cache eth dest pointer before skb pull

[ Upstream commit 2446a68 ]

Don't cache eth dest pointer before calling pskb_may_pull.

Fixes: cf0f02d ("[BRIDGE]: use llc for receiving STP packets")
Signed-off-by: Nikolay Aleksandrov <nikolay@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: Nikolay Aleksandrov

net/bridge/br_stp_bpdu.c

@@ -147,7 +147,6 @@ void br_send_tcn_bpdu(struct net_bridge_port *p)
 void br_stp_rcv(const struct stp_proto *proto, struct sk_buff *skb,
 		struct net_device *dev)
 {
-	const unsigned char *dest = eth_hdr(skb)->h_dest;
 	struct net_bridge_port *p;
 	struct net_bridge *br;
 	const unsigned char *buf;
@@ -176,7 +175,7 @@ void br_stp_rcv(const struct stp_proto *proto, struct sk_buff *skb,
 	if (p->state == BR_STATE_DISABLED)
 		goto out;
 
-	if (!ether_addr_equal(dest, br->group_addr))
+	if (!ether_addr_equal(eth_hdr(skb)->h_dest, br->group_addr))
 		goto out;
 
 	if (p->flags & BR_BPDU_GUARD) {