mac80211: free skb in WEP error case

If, for some strange reason, ieee80211_wep_encrypt() fails in
ieee80211_send_auth() free the SKB instead of sending out the
useless frame, in addition to the warning. This can't really
happen since the SKB was freshly allocated.
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20210618133832.98f058d7a8b2.Ie605e6a10e72eae02f5734032826af48b85b6d11@changeidSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/util.c

@@ -1693,7 +1693,10 @@ void ieee80211_send_auth(struct ieee80211_sub_if_data *sdata,
 	if (auth_alg == WLAN_AUTH_SHARED_KEY && transaction == 3) {
 		mgmt->frame_control |= cpu_to_le16(IEEE80211_FCTL_PROTECTED);
 		err = ieee80211_wep_encrypt(local, skb, key, key_len, key_idx);
-		WARN_ON(err);
+		if (WARN_ON(err)) {
+			kfree_skb(skb);
+			return;
+		}
 	}
 
 	IEEE80211_SKB_CB(skb)->flags |= IEEE80211_TX_INTFL_DONT_ENCRYPT |