Subject: Re: [PATCH net RESEND] bridge: flush br's address entry in fdb when remove the bridge dev

From: Vlad Yasevich <[email-masked]>
Date: Tue, 19 Nov 2013 10:52:06 -0500

On 11/18/2013 09:57 PM, Ding Tianhong wrote:
> When the following commands are executed:
> 
> brctl addbr br0
> ifconfig br0 hw ether <addr>
> rmmod bridge
> 
> The calltrace will occur:
> 
> [  563.312114] device eth1 left promiscuous mode
> [  563.312188] br0: port 1(eth1) entered disabled state
> [  563.468190] kmem_cache_destroy bridge_fdb_cache: Slab cache still has objects
> [  563.468197] CPU: 6 PID: 6982 Comm: rmmod Tainted: G           O 3.12.0-0.7-default+ #9
> [  563.468199] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007
> [  563.468200]  0000000000000880 ffff88010f111e98 ffffffff814d1c92 ffff88010f111eb8
> [  563.468204]  ffffffff81148efd ffff88010f111eb8 0000000000000000 ffff88010f111ec8
> [  563.468206]  ffffffffa062a270 ffff88010f111ed8 ffffffffa063ac76 ffff88010f111f78
> [  563.468209] Call Trace:
> [  563.468218]  [<ffffffff814d1c92>] dump_stack+0x6a/0x78
> [  563.468234]  [<ffffffff81148efd>] kmem_cache_destroy+0xfd/0x100
> [  563.468242]  [<ffffffffa062a270>] br_fdb_fini+0x10/0x20 [bridge]
> [  563.468247]  [<ffffffffa063ac76>] br_deinit+0x4e/0x50 [bridge]
> [  563.468254]  [<ffffffff810c7dc9>] SyS_delete_module+0x199/0x2b0
> [  563.468259]  [<ffffffff814e0922>] system_call_fastpath+0x16/0x1b
> [  570.377958] Bridge firewalling registered
> 
> ------------------------------------------------
> 
> The reason is that when the bridge dev's address is changed, the
> br_fdb_change_mac_address() will add new address in fdb, but when
> the bridge was removed, the address entry in the fdb did not free,
> the bridge_fdb_cache still has objects when destroy the cache, Fix
> this by flushing the bridge address entry when removing the bridge.
> 
> Signed-off-by: Ding Tianhong <[email-masked]>
> ---
>  net/bridge/br_if.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/net/bridge/br_if.c b/net/bridge/br_if.c
> index 6e6194f..98084d8 100644
> --- a/net/bridge/br_if.c
> +++ b/net/bridge/br_if.c
> @@ -172,6 +172,10 @@ void br_dev_delete(struct net_device *dev, struct list_head *head)
>  		del_nbp(p);
>  	}
>  
> +	spin_lock_bh(&br->hash_lock);
> +	fdb_delete_by_addr(br, br->dev->dev_addr, 0);
> +	spin_unlock_bh(&br->hash_lock);
> +
>  	br_vlan_flush(br);
>  	del_timer_sync(&br->gc_timer);
>  
> 

I think you need to use fdb_delete_by_port(br, NULL, 1);  here.

The reason is that if the bridge had vlan filtering configured, when the
bridge mac address was changed, an fdb would have been created for
for ever vlan configured on the bridge.  You delete only vlan0, so you
would still have a leak.

-vlad