BRIDGE: Properly dereference the br_should_route_hook

[BRIDGE]: Properly dereference the br_should_route_hook

[ Upstream commit: 82de382ce8e1c7645984616728dc7aaa057821e4 ]

This hook is protected with the RCU, so simple

if (br_should_route_hook)
	br_should_route_hook(...)

is not enough on some architectures.

Use the rcu_dereference/rcu_assign_pointer in this case.

Fixed Stephen's comment concerning using the typeof().

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 420bbb9955e93fa2480393292e7b2705d1cc7a28..fb2c7cc6bb7e8184db9fe5eb05129ed923b06230 100644 (file)
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -127,6 +127,7 @@ static inline int is_link_local(const unsigned char *dest)
 struct sk_buff *br_handle_frame(struct net_bridge_port *p, struct sk_buff *skb)
 {
        const unsigned char *dest = eth_hdr(skb)->h_dest;
+       int (*rhook)(struct sk_buff **pskb);
 
        if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
                goto drop;
@@ -148,9 +149,9 @@ struct sk_buff *br_handle_frame(struct net_bridge_port *p, struct sk_buff *skb)
 
        switch (p->state) {
        case BR_STATE_FORWARDING:
-
-               if (br_should_route_hook) {
-                       if (br_should_route_hook(&skb))
+               rhook = rcu_dereference(br_should_route_hook);
+               if (rhook != NULL) {
+                       if (rhook(&skb))
                                return skb;
                        dest = eth_hdr(skb)->h_dest;
                }

diff --git a/net/bridge/netfilter/ebtable_broute.c b/net/bridge/netfilter/ebtable_broute.c
index d37ce04789388028b2b8a56803c2e17658fc42c4..bc17cf5298024447fa45409de3708347da57f116 100644 (file)
--- a/net/bridge/netfilter/ebtable_broute.c
+++ b/net/bridge/netfilter/ebtable_broute.c
@@ -70,13 +70,13 @@ static int __init ebtable_broute_init(void)
        if (ret < 0)
                return ret;
        /* see br_input.c */
-       br_should_route_hook = ebt_broute;
+       rcu_assign_pointer(br_should_route_hook, ebt_broute);
        return ret;
 }
 
 static void __exit ebtable_broute_fini(void)
 {
-       br_should_route_hook = NULL;
+       rcu_assign_pointer(br_should_route_hook, NULL);
        synchronize_net();
        ebt_unregister_table(&broute_table);
 }