linux-kernel - [PATCH 3.16 33/47] net: bridge: stp: don't cache eth dest pointer before skb pull

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Message-ID: <lsq.1572026582.518697203@decadent.org.uk>
Date:   Fri, 25 Oct 2019 19:03:34 +0100
From:   Ben Hutchings <ben@...adent.org.uk>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:     akpm@...ux-foundation.org, Denis Kirjanov <kda@...ux-powerpc.org>,
        "David S. Miller" <davem@...emloft.net>,
        "Nikolay Aleksandrov" <nikolay@...ulusnetworks.com>
Subject: [PATCH 3.16 33/47] net: bridge: stp: don't cache eth dest pointer
 before skb pull

3.16.76-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>

commit 2446a68ae6a8cee6d480e2f5b52f5007c7c41312 upstream.

Don't cache eth dest pointer before calling pskb_may_pull.

Fixes: cf0f02d04a83 ("[BRIDGE]: use llc for receiving STP packets")
Signed-off-by: Nikolay Aleksandrov <nikolay@...ulusnetworks.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 net/bridge/br_stp_bpdu.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

--- a/net/bridge/br_stp_bpdu.c
+++ b/net/bridge/br_stp_bpdu.c
@@ -140,7 +140,6 @@ void br_send_tcn_bpdu(struct net_bridge_
 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;
@@ -169,7 +168,7 @@ void br_stp_rcv(const struct stp_proto *
 	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) {