mptcp: deduplicate error paths on endpoint creation

When endpoint creation fails, we need to free the newly allocated
entry and eventually destroy the paired mptcp listener socket.

Consolidate such action in a single point let all the errors path
reach it.
Reviewed-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NPaolo Abeni <pabeni@redhat.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/mptcp/pm_netlink.c

@@ -1003,16 +1003,12 @@ static int mptcp_pm_nl_create_listen_socket(struct sock *sk,
 		return err;
 
 	msk = mptcp_sk(entry->lsk->sk);
-	if (!msk) {
-		err = -EINVAL;
-		goto out;
-	}
+	if (!msk)
+		return -EINVAL;
 
 	ssock = __mptcp_nmpc_socket(msk);
-	if (!ssock) {
-		err = -EINVAL;
-		goto out;
-	}
+	if (!ssock)
+		return -EINVAL;
 
 	mptcp_info2sockaddr(&entry->addr, &addr, entry->addr.family);
 #if IS_ENABLED(CONFIG_MPTCP_IPV6)
@@ -1022,20 +1018,16 @@ static int mptcp_pm_nl_create_listen_socket(struct sock *sk,
 	err = kernel_bind(ssock, (struct sockaddr *)&addr, addrlen);
 	if (err) {
 		pr_warn("kernel_bind error, err=%d", err);
-		goto out;
+		return err;
 	}
 
 	err = kernel_listen(ssock, backlog);
 	if (err) {
 		pr_warn("kernel_listen error, err=%d", err);
-		goto out;
+		return err;
 	}
 
 	return 0;
-
-out:
-	sock_release(entry->lsk);
-	return err;
 }
 
 int mptcp_pm_nl_get_local_id(struct mptcp_sock *msk, struct sock_common *skc)
@@ -1327,7 +1319,7 @@ static int mptcp_nl_cmd_add_addr(struct sk_buff *skb, struct genl_info *info)
 		return -EINVAL;
 	}
 
-	entry = kmalloc(sizeof(*entry), GFP_KERNEL_ACCOUNT);
+	entry = kzalloc(sizeof(*entry), GFP_KERNEL_ACCOUNT);
 	if (!entry) {
 		GENL_SET_ERR_MSG(info, "can't allocate addr");
 		return -ENOMEM;
@@ -1338,22 +1330,21 @@ static int mptcp_nl_cmd_add_addr(struct sk_buff *skb, struct genl_info *info)
 		ret = mptcp_pm_nl_create_listen_socket(skb->sk, entry);
 		if (ret) {
 			GENL_SET_ERR_MSG(info, "create listen socket error");
-			kfree(entry);
-			return ret;
+			goto out_free;
 		}
 	}
 	ret = mptcp_pm_nl_append_new_local_addr(pernet, entry);
 	if (ret < 0) {
 		GENL_SET_ERR_MSG(info, "too many addresses or duplicate one");
-		if (entry->lsk)
-			sock_release(entry->lsk);
-		kfree(entry);
-		return ret;
+		goto out_free;
 	}
 
 	mptcp_nl_add_subflow_or_signal_addr(sock_net(skb->sk));
-
 	return 0;
+
+out_free:
+	__mptcp_pm_release_addr_entry(entry);
+	return ret;
 }
 
 int mptcp_pm_get_flags_and_ifindex_by_id(struct mptcp_sock *msk, unsigned int id,