mac80211: clear ifmgd->bssid only after building DELBA

ieee80211_set_disassoc() clears ifmgd->bssid before
building DELBA frames, resulting in frames with invalid
bssid ("00:00:00:00:00:00").

Fix it by clearing ifmgd->bssid only after building
all the needed frames.

After this change, we no longer need to save the
bssid (before clearing it), so remove the local array.

Reported-by: Ido Yariv <ido@wizery.com>
Cc: stable@vger.kernel.org
Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/mlme.c

@@ -1342,7 +1342,6 @@ static void ieee80211_set_disassoc(struct ieee80211_sub_if_data *sdata,
 	struct ieee80211_local *local = sdata->local;
 	struct sta_info *sta;
 	u32 changed = 0;
-	u8 bssid[ETH_ALEN];
 
 	ASSERT_MGD_MTX(ifmgd);
 
@@ -1354,10 +1353,7 @@ static void ieee80211_set_disassoc(struct ieee80211_sub_if_data *sdata,
 
 	ieee80211_stop_poll(sdata);
 
-	memcpy(bssid, ifmgd->associated->bssid, ETH_ALEN);
-
 	ifmgd->associated = NULL;
-	memset(ifmgd->bssid, 0, ETH_ALEN);
 
 	/*
 	 * we need to commit the associated = NULL change because the
@@ -1377,7 +1373,7 @@ static void ieee80211_set_disassoc(struct ieee80211_sub_if_data *sdata,
 	netif_carrier_off(sdata->dev);
 
 	mutex_lock(&local->sta_mtx);
-	sta = sta_info_get(sdata, bssid);
+	sta = sta_info_get(sdata, ifmgd->bssid);
 	if (sta) {
 		set_sta_flag(sta, WLAN_STA_BLOCK_BA);
 		ieee80211_sta_tear_down_BA_sessions(sta, tx);
@@ -1386,13 +1382,16 @@ static void ieee80211_set_disassoc(struct ieee80211_sub_if_data *sdata,
 
 	/* deauthenticate/disassociate now */
 	if (tx || frame_buf)
-		ieee80211_send_deauth_disassoc(sdata, bssid, stype, reason,
-					       tx, frame_buf);
+		ieee80211_send_deauth_disassoc(sdata, ifmgd->bssid, stype,
+					       reason, tx, frame_buf);
 
 	/* flush out frame */
 	if (tx)
 		drv_flush(local, false);
 
+	/* clear bssid only after building the needed mgmt frames */
+	memset(ifmgd->bssid, 0, ETH_ALEN);
+
 	/* remove AP and TDLS peers */
 	sta_info_flush(local, sdata);