mac80211: Add netif state checking to ieee80211_ifa_changed

There's a window for ieee80211_ifa_changed() to get called whilst the
managed mode mutex has not been initialized when opening and stopping the
interface. Currently this causes a kernel BUG like the following:

[  132.460013] kernel BUG at /home/wifi/iwlwifi-2.6/net/mac80211/main.c:380!
[  132.460013] invalid opcode: 0000 [#1] SMP

The mutex is initialized during open(), hence once netif_running() is true,
the mutex should be valid. Fix by adding a netif_running() check to the
function.

Reported-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Tested-by: Reinette Chatre <reinette.chatre@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

1 files changed, 3 insertions, 0 deletions

diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 5706156d1ecf..88b671a16a41 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -359,6 +359,9 @@ static int ieee80211_ifa_changed(struct notifier_block *nb,
         struct ieee80211_sub_if_data *sdata;
         struct ieee80211_if_managed *ifmgd;
 
+        if (!netif_running(ndev))
+                return NOTIFY_DONE;
+
         /* Make sure it's our interface that got changed */
         if (!wdev)
                 return NOTIFY_DONE;