mac80211: fix possible sta leak

If TDLS station addition is rejected, the sta memory is leaked.
Avoid this by moving the check before the allocation.

Cc: stable@vger.kernel.org
Fixes: 7ed52853 ("mac80211: don't initiate TDLS connection if station is not associated to AP")
Link: https://lore.kernel.org/r/20190801073033.7892-1-johannes@sipsolutions.netSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/cfg.c

@@ -1546,6 +1546,11 @@ static int ieee80211_add_station(struct wiphy *wiphy, struct net_device *dev,
 	if (is_multicast_ether_addr(mac))
 		return -EINVAL;
 
+	if (params->sta_flags_set & BIT(NL80211_STA_FLAG_TDLS_PEER) &&
+	    sdata->vif.type == NL80211_IFTYPE_STATION &&
+	    !sdata->u.mgd.associated)
+		return -EINVAL;
+
 	sta = sta_info_alloc(sdata, mac, GFP_KERNEL);
 	if (!sta)
 		return -ENOMEM;
@@ -1553,10 +1558,6 @@ static int ieee80211_add_station(struct wiphy *wiphy, struct net_device *dev,
 	if (params->sta_flags_set & BIT(NL80211_STA_FLAG_TDLS_PEER))
 		sta->sta.tdls = true;
 
-	if (sta->sta.tdls && sdata->vif.type == NL80211_IFTYPE_STATION &&
-	    !sdata->u.mgd.associated)
-		return -EINVAL;
-
 	err = sta_apply_parameters(local, sta, params);
 	if (err) {
 		sta_info_free(local, sta);