HI Eric
the problem is as follow:
br_del_if()-->del_nbp():
list_del_rcu(&p->list);
dev->priv_flags &= ~IFF_BRIDGE_PORT;
------>at this point, the nic be deleting still have rx_handler , so , may in br_handle_frame()
------>br_port_exists() will return false,so br_get_port_rcu() will return NULL
------>so in br_handle_frame , there will be a null panic.
netdev_rx_handler_unregister(dev);
synchronize_net();
i have checked commit 00cfec37484761a44, i think it didn't fix this bug..
thanks.
On Thu, Jun 20, 2013 at 12:55 PM, Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote:
On Thu, 2013-06-20 at 11:08 +0800, xiaoming gao wrote:Please check current version before sending a patch.
> From: newtongao <newtongao@xxxxxxxxxxx>
> Date: Wed, 19 Jun 2013 14:58:33 +0800
> Subject: [PATCH] net bridge: add null pointer check,fix panic
>
> in kernel 3.0, br_port_get_rcu() may return NULL when network interface be deleting from bridge,
> but in function br_handle_frame and br_handle_local_finish, the pointer didn't be checked before using,
> so all br_port_get_rcu callers must do null check,or there occurs the null pointer panic.
>
> kernel 3.4 also has this bug,i have verified.
> mainline kernel still did not check br_port_get_rcu()'s NULL pointer, but i have not tested it yet.
This was most probably fixed in commit 00cfec37484761a44
("net: add a synchronize_net() in netdev_rx_handler_unregister()")
Thanks
