Re: [PATCH] mac80211: fix conn_mon_timer running after disassociate

[Johannes Berg <johannes@sipsolutions.net>]

On Wed, 2011-02-16 at 10:54 +0100, Stanislaw Gruszka wrote:
> Low level driver could pass rx frames to us after disassociate, what
> can lead to run conn_mon_timer by ieee80211_sta_rx_notify(). Thats
> is obviously wrong, but nothing happens until we unload modules and
> resources are used after free. If kernel debugging is enabled following
> warning could be observed:
> 
> WARNING: at lib/debugobjects.c:259 debug_print_object+0x65/0x70()
> Hardware name: HP xw8600 Workstation
> ODEBUG: free active (active state 0) object type: timer_list
> Modules linked in: iwlagn(-) iwlcore mac80211 cfg80211 ...
> Pid: 13827, comm: rmmod Tainted: G        W   2.6.38-rc4-wl+ #22
> Call Trace:
>  [<ffffffff810649cf>] ? warn_slowpath_common+0x7f/0xc0
>  [<ffffffff81064ac6>] ? warn_slowpath_fmt+0x46/0x50
>  [<ffffffff81226fc5>] ? debug_print_object+0x65/0x70
>  [<ffffffff81227625>] ? debug_check_no_obj_freed+0x125/0x210
>  [<ffffffff8109ebd7>] ? debug_check_no_locks_freed+0xf7/0x170
>  [<ffffffff81156092>] ? kfree+0xc2/0x2f0
>  [<ffffffff813ec5c5>] ? netdev_release+0x45/0x60
>  [<ffffffff812f1067>] ? device_release+0x27/0xa0
>  [<ffffffff81216ddd>] ? kobject_release+0x8d/0x1a0
>  [<ffffffff81216d50>] ? kobject_release+0x0/0x1a0
>  [<ffffffff812183b7>] ? kref_put+0x37/0x70
>  [<ffffffff81216c57>] ? kobject_put+0x27/0x60
>  [<ffffffff813d5d1b>] ? netdev_run_todo+0x1ab/0x270
>  [<ffffffff813e771e>] ? rtnl_unlock+0xe/0x10
>  [<ffffffffa0581188>] ? ieee80211_unregister_hw+0x58/0x120 [mac80211]
>  [<ffffffffa0377ed7>] ? iwl_pci_remove+0xdb/0x22a [iwlagn]
>  [<ffffffff8123cde2>] ? pci_device_remove+0x52/0x120
>  [<ffffffff812f5205>] ? __device_release_driver+0x75/0xe0
>  [<ffffffff812f5348>] ? driver_detach+0xd8/0xe0
>  [<ffffffff812f4111>] ? bus_remove_driver+0x91/0x100
>  [<ffffffff812f5b62>] ? driver_unregister+0x62/0xa0
>  [<ffffffff8123d194>] ? pci_unregister_driver+0x44/0xa0
>  [<ffffffffa0377df5>] ? iwl_exit+0x15/0x1c [iwlagn]
>  [<ffffffff810ab492>] ? sys_delete_module+0x1a2/0x270
>  [<ffffffff81498889>] ? trace_hardirqs_on_thunk+0x3a/0x3f
>  [<ffffffff8100bf42>] ? system_call_fastpath+0x16/0x1b
> 
> Signed-off-by: Stanislaw Gruszka <sgruszka@redhat.com>
> ---
>  net/mac80211/mlme.c |    6 ++++++
>  1 files changed, 6 insertions(+), 0 deletions(-)
> 
> diff --git a/net/mac80211/mlme.c b/net/mac80211/mlme.c
> index d89e878..7b3f9df 100644
> --- a/net/mac80211/mlme.c
> +++ b/net/mac80211/mlme.c
> @@ -1071,6 +1071,12 @@ void ieee80211_sta_rx_notify(struct ieee80211_sub_if_data *sdata,
>  	if (is_multicast_ether_addr(hdr->addr1))
>  		return;
>  
> +	/*
> +	 * In case we receive pending frames after disassociation.
> +	 */
> +	if (!sdata->u.mgd.associated)
> +		return;
> +
>  	ieee80211_sta_reset_conn_monitor(sdata);
>  }
>  

good catch, thanks.

johannes