mac80211: fix work removal on deauth request

When deauth is requested while an auth or assoc
work item is in progress, we currently delete it
without regard for any state it might need to
clean up. Fix it by cleaning up for those items.

In the case Pontus found, the problem manifested
itself as such:

authenticate with 00:23:69:aa:dd:7b (try 1)
authenticated
failed to insert Dummy STA entry for the AP (error -17)
deauthenticating from 00:23:69:aa:dd:7b by local choice (reason=2)

It could also happen differently if the driver
uses the tx_sync callback.

We can't just call the ->done() method of the work
items because that will lock up due to the locking
in cfg80211. This fix isn't very clean, but that
seems acceptable since I have patches pending to
remove this code completely.

Cc: stable@vger.kernel.org
Reported-by: Pontus Fuchs <pontus.fuchs@gmail.com>
Tested-by: Pontus Fuchs <pontus.fuchs@gmail.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

net/mac80211/mlme.c

@@ -2750,7 +2750,6 @@ int ieee80211_mgd_deauth(struct ieee80211_sub_if_data *sdata,
 {
 	struct ieee80211_local *local = sdata->local;
 	struct ieee80211_if_managed *ifmgd = &sdata->u.mgd;
-	struct ieee80211_work *wk;
 	u8 bssid[ETH_ALEN];
 	bool assoc_bss = false;
 
@@ -2763,30 +2762,47 @@ int ieee80211_mgd_deauth(struct ieee80211_sub_if_data *sdata,
 		assoc_bss = true;
 	} else {
 		bool not_auth_yet = false;
+		struct ieee80211_work *tmp, *wk = NULL;
 
 		mutex_unlock(&ifmgd->mtx);
 
 		mutex_lock(&local->mtx);
-		list_for_each_entry(wk, &local->work_list, list) {
-			if (wk->sdata != sdata)
+		list_for_each_entry(tmp, &local->work_list, list) {
+			if (tmp->sdata != sdata)
 				continue;
 
-			if (wk->type != IEEE80211_WORK_DIRECT_PROBE &&
-			    wk->type != IEEE80211_WORK_AUTH &&
-			    wk->type != IEEE80211_WORK_ASSOC &&
-			    wk->type != IEEE80211_WORK_ASSOC_BEACON_WAIT)
+			if (tmp->type != IEEE80211_WORK_DIRECT_PROBE &&
+			    tmp->type != IEEE80211_WORK_AUTH &&
+			    tmp->type != IEEE80211_WORK_ASSOC &&
+			    tmp->type != IEEE80211_WORK_ASSOC_BEACON_WAIT)
 				continue;
 
-			if (memcmp(req->bss->bssid, wk->filter_ta, ETH_ALEN))
+			if (memcmp(req->bss->bssid, tmp->filter_ta, ETH_ALEN))
 				continue;
 
-			not_auth_yet = wk->type == IEEE80211_WORK_DIRECT_PROBE;
-			list_del_rcu(&wk->list);
-			free_work(wk);
+			not_auth_yet = tmp->type == IEEE80211_WORK_DIRECT_PROBE;
+			list_del_rcu(&tmp->list);
+			synchronize_rcu();
+			wk = tmp;
 			break;
 		}
 		mutex_unlock(&local->mtx);
 
+		if (wk && wk->type == IEEE80211_WORK_ASSOC) {
+			/* clean up dummy sta & TX sync */
+			sta_info_destroy_addr(wk->sdata, wk->filter_ta);
+			if (wk->assoc.synced)
+				drv_finish_tx_sync(local, wk->sdata,
+						   wk->filter_ta,
+						   IEEE80211_TX_SYNC_ASSOC);
+		} else if (wk && wk->type == IEEE80211_WORK_AUTH) {
+			if (wk->probe_auth.synced)
+				drv_finish_tx_sync(local, wk->sdata,
+						   wk->filter_ta,
+						   IEEE80211_TX_SYNC_AUTH);
+		}
+		kfree(wk);
+
 		/*
 		 * If somebody requests authentication and we haven't
 		 * sent out an auth frame yet there's no need to send