mac80211: Do not free net device after it is unregistered.

The error path in ieee80211_register_hw() may call the unregister_netdev()
and right after it - the free_netdev(), which is wrong, since the
unregister releases the device itself.

So the proposed fix is to NULL the local->mdev after unregister is done
and check this before calling free_netdev().

I checked - no code uses the local->mdev after unregister in this error
path (but even if some did this would be a BUG).

Signed-off-by: Pavel Emelyanov <xemul@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 5 insertions, 2 deletions

diff --git a/net/mac80211/main.c b/net/mac80211/main.c
index 9ad4e3631b6b..915afadb0602 100644
--- a/net/mac80211/main.c
+++ b/net/mac80211/main.c
@@ -1766,6 +1766,7 @@ fail_wep:
 fail_rate:
         ieee80211_debugfs_remove_netdev(IEEE80211_DEV_TO_SUB_IF(local->mdev));
         unregister_netdevice(local->mdev);
+        local->mdev = NULL;
 fail_dev:
         rtnl_unlock();
         sta_info_stop(local);
@@ -1773,8 +1774,10 @@ fail_sta_info:
         debugfs_hw_del(local);
         destroy_workqueue(local->hw.workqueue);
 fail_workqueue:
-        ieee80211_if_free(local->mdev);
-        local->mdev = NULL;
+        if (local->mdev != NULL) {
+                ieee80211_if_free(local->mdev);
+                local->mdev = NULL;
+        }
 fail_mdev_alloc:
         wiphy_unregister(local->hw.wiphy);
         return result;