3.11-stable review patch. If anyone has any objections, please let me know.
------------------
From: Hong Zhiguo <zhiguohong@xxxxxxxxxxx>
[ Upstream commit 716ec052d2280d511e10e90ad54a86f5b5d4dcc2 ]
The NULL deref happens when br_handle_frame is called between these
2 lines of del_nbp:
dev->priv_flags &= ~IFF_BRIDGE_PORT;
/* --> br_handle_frame is called at this time */
netdev_rx_handler_unregister(dev);
In br_handle_frame the return of br_port_get_rcu(dev) is dereferenced
without check but br_port_get_rcu(dev) returns NULL if:
!(dev->priv_flags & IFF_BRIDGE_PORT)
Eric Dumazet pointed out the testing of IFF_BRIDGE_PORT is not necessary
here since we're in rcu_read_lock and we have synchronize_net() in
netdev_rx_handler_unregister. So remove the testing of IFF_BRIDGE_PORT
and by the previous patch, make sure br_port_get_rcu is called in
bridging code.
Signed-off-by: Hong Zhiguo <zhiguohong@xxxxxxxxxxx>
Acked-by: Eric Dumazet <edumazet@xxxxxxxxxx>
Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
net/bridge/br_private.h | 5 +----
1 file changed, 1 insertion(+), 4 deletions(-)
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -202,10 +202,7 @@ struct net_bridge_port
static inline struct net_bridge_port *br_port_get_rcu(const struct net_device *dev)
{
- struct net_bridge_port *port =
- rcu_dereference_rtnl(dev->rx_handler_data);
-
- return br_port_exists(dev) ? port : NULL;
+ return rcu_dereference(dev->rx_handler_data);
}
static inline struct net_bridge_port *br_port_get_rtnl(const struct net_device *dev)
--
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