[patch 59/60] BRIDGE: Properly dereference the br_should_route_hook

Greg KH
2007-12-13T07:20:53Z

[-- Attachment #1: bridge-properly-dereference-the-br_should_route_hook.patch --]
[-- Type: text/plain, Size: 2038 bytes --]

2.6.23-stable review patch. If anyone has any objections, please let us
know.

------------------
From: Pavel Emelyanov <xemul@openvz.org>

[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>

---
net/bridge/br_input.c | 7 ++++---
net/bridge/netfilter/ebtable_broute.c | 4 ++--
2 files changed, 6 insertions(+), 5 deletions(-)

--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -122,6 +122,7 @@ static inline int is_link_local(const un
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;
@@ -143,9 +144,9 @@ struct sk_buff *br_handle_frame(struct n

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;
}
--- a/net/bridge/netfilter/ebtable_broute.c
+++ b/net/bridge/netfilter/ebtable_broute.c
@@ -70,13 +70,13 @@ static int __init ebtable_broute_init(vo
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);
}

--