bridge: kernel panic when unloading bridge module

There is a race condition when unloading bridge and netfilter.

The problem happens if __fake_rtable is in use by a skb
coming in, while someone starts to unload bridge.ko.
br_netfilter_fini() is called at the beginning of unload
in br_deinit() while skbs still are being forwarded and
transferred to local ip stack. Thus there is a possibility
of the __fake_rtable pointer not being removed in a skb that
goes up to ip stack. This results in a kernel panic, as
ip_rcv() calls the input-function of __fake_rtable, which
is NULL.

Moving the call of br_netfilter_fini() to the end of
br_deinit() solves the problem.

Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
Signed-off-by: Stephen Hemminger <stephen.hemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/bridge/br.c b/net/bridge/br.c
index a9018287312071c4cd77a442b062b7444c7b72bf..8f3c58e5f7a562d88abdd9df744bf77fb65663c6 100644 (file)
--- a/net/bridge/br.c
+++ b/net/bridge/br.c
@@ -76,7 +76,6 @@ static void __exit br_deinit(void)
        rcu_assign_pointer(br_stp_sap->rcv_func, NULL);
 
        br_netlink_fini();
-       br_netfilter_fini();
        unregister_netdevice_notifier(&br_device_notifier);
        brioctl_set(NULL);
 
@@ -84,6 +83,7 @@ static void __exit br_deinit(void)
 
        synchronize_net();
 
+       br_netfilter_fini();
        llc_sap_put(br_stp_sap);
        br_fdb_get_hook = NULL;
        br_fdb_put_hook = NULL;