From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stephen Hemminger Subject: [PATCH 2/2] bridge: kernel panic when unloading bridge module Date: Mon, 28 Apr 2008 17:29:07 -0700 Message-ID: <20080428172907.2517c12e@extreme> References: <20080428172809.7f814ed5@extreme> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: netdev@vger.kernel.org, Bodo Stroesser To: David Miller Return-path: Received: from mail.vyatta.com ([216.93.170.194]:44333 "EHLO mail.vyatta.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S936152AbYD2A3g (ORCPT ); Mon, 28 Apr 2008 20:29:36 -0400 In-Reply-To: <20080428172809.7f814ed5@extreme> Sender: netdev-owner@vger.kernel.org List-ID: 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 Signed-off-by: Stephen Hemminger --- net/bridge/br.c | 2 +- 1 files changed, 1 insertions(+), 1 deletions(-) --- a/net/bridge/br.c 2008-04-28 15:27:06.000000000 -0700 +++ b/net/bridge/br.c 2008-04-28 15:31:32.000000000 -0700 @@ -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;