nl80211: fix nl80211_send_iface() error paths

Evidently I introduced a locking bug in my change here,
the nla_put_failure sometimes needs to unlock. Fix it.

Fixes: 44905265bc ("nl80211: don't expose wdev->ssid for most interfaces")
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/wireless/nl80211.c

@@ -2610,7 +2610,7 @@ static int nl80211_send_iface(struct sk_buff *msg, u32 portid, u32 seq, int flag
 	case NL80211_IFTYPE_AP:
 		if (wdev->ssid_len &&
 		    nla_put(msg, NL80211_ATTR_SSID, wdev->ssid_len, wdev->ssid))
-			goto nla_put_failure;
+			goto nla_put_failure_locked;
 		break;
 	case NL80211_IFTYPE_STATION:
 	case NL80211_IFTYPE_P2P_CLIENT:
@@ -2623,7 +2623,7 @@ static int nl80211_send_iface(struct sk_buff *msg, u32 portid, u32 seq, int flag
 		if (!ssid_ie)
 			break;
 		if (nla_put(msg, NL80211_ATTR_SSID, ssid_ie[1], ssid_ie + 2))
-			goto nla_put_failure;
+			goto nla_put_failure_locked;
 		break;
 		}
 	default:
@@ -2635,6 +2635,8 @@ static int nl80211_send_iface(struct sk_buff *msg, u32 portid, u32 seq, int flag
 	genlmsg_end(msg, hdr);
 	return 0;
 
+ nla_put_failure_locked:
+	wdev_unlock(wdev);
  nla_put_failure:
 	genlmsg_cancel(msg, hdr);
 	return -EMSGSIZE;