Linux Ethernet Bridging - Apr 2008 - [Bridge] bridge: kernel panic when unloading bridge.ko

Hi,

here is a patch for 2.6.22.5, but AFAICS it is relevant
for 2.6.25 also.

Please CC me, I'm not on the list.

Best regards
Bodo


===========================================================There is a race
condition when unloading bridge.ko

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 at fujitsu-siemens.com>
---
 net/bridge/br.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Index: linux-2.6.22.5-31/net/bridge/br.c
==================================================================---
linux-2.6.22.5-31.orig/net/bridge/br.c
+++ linux-2.6.22.5-31/net/bridge/br.c
@@ -74,7 +74,6 @@ 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);
 
@@ -82,6 +81,7 @@ 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;