mac80211: skb leak in mesh_plink_frame_tx()

Although adding an IE is almost guaranteed to succeed since we already
accounted for its length while allocating the skb, we should still free
the skb in case of failure.
Signed-off-by: Thomas Pedersen <thomas@cozybit.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/mesh_plink.c

@@ -224,6 +224,7 @@ static int mesh_plink_frame_tx(struct ieee80211_sub_if_data *sdata,
 	u8 *pos, ie_len = 4;
 	int hdr_len = offsetof(struct ieee80211_mgmt, u.action.u.self_prot) +
 		      sizeof(mgmt->u.action.u.self_prot);
+	int err = -ENOMEM;
 
 	skb = dev_alloc_skb(local->tx_headroom +
 			    hdr_len +
@@ -267,11 +268,11 @@ static int mesh_plink_frame_tx(struct ieee80211_sub_if_data *sdata,
 		    mesh_add_rsn_ie(skb, sdata) ||
 		    mesh_add_meshid_ie(skb, sdata) ||
 		    mesh_add_meshconf_ie(skb, sdata))
-			return -1;
+			goto free;
 	} else {	/* WLAN_SP_MESH_PEERING_CLOSE */
 		info->flags |= IEEE80211_TX_CTL_NO_ACK;
 		if (mesh_add_meshid_ie(skb, sdata))
-			return -1;
+			goto free;
 	}
 
 	/* Add Mesh Peering Management element */
@@ -290,11 +291,12 @@ static int mesh_plink_frame_tx(struct ieee80211_sub_if_data *sdata,
 		ie_len += 2;	/* reason code */
 		break;
 	default:
-		return -EINVAL;
+		err = -EINVAL;
+		goto free;
 	}
 
 	if (WARN_ON(skb_tailroom(skb) < 2 + ie_len))
-		return -ENOMEM;
+		goto free;
 
 	pos = skb_put(skb, 2 + ie_len);
 	*pos++ = WLAN_EID_PEER_MGMT;
@@ -315,14 +317,17 @@ static int mesh_plink_frame_tx(struct ieee80211_sub_if_data *sdata,
 	if (action != WLAN_SP_MESH_PEERING_CLOSE) {
 		if (mesh_add_ht_cap_ie(skb, sdata) ||
 		    mesh_add_ht_oper_ie(skb, sdata))
-			return -1;
+			goto free;
 	}
 
 	if (mesh_add_vendor_ies(skb, sdata))
-		return -1;
+		goto free;
 
 	ieee80211_tx_skb(sdata, skb);
 	return 0;
+free:
+	kfree_skb(skb);
+	return err;
 }
 
 /**