mptcp: netlink: fix some error return code

Fix to return negative error code -EINVAL from some error handling
case instead of 0, as done elsewhere in those functions.

Fixes: 9ab4807c ("mptcp: netlink: Add MPTCP_PM_CMD_ANNOUNCE")
Fixes: 702c2f64 ("mptcp: netlink: allow userspace-driven subflow establishment")
Cc: stable@vger.kernel.org
Reviewed-by: NMatthieu Baerts <matthieu.baerts@tessares.net>
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: NMat Martineau <mathew.j.martineau@linux.intel.com>
Signed-off-by: NJakub Kicinski <kuba@kernel.org>

net/mptcp/pm_userspace.c

@@ -156,6 +156,7 @@ int mptcp_nl_cmd_announce(struct sk_buff *skb, struct genl_info *info)
 
 	if (addr_val.addr.id == 0 || !(addr_val.flags & MPTCP_PM_ADDR_FLAG_SIGNAL)) {
 		GENL_SET_ERR_MSG(info, "invalid addr id or flags");
+		err = -EINVAL;
 		goto announce_err;
 	}
 
@@ -282,6 +283,7 @@ int mptcp_nl_cmd_sf_create(struct sk_buff *skb, struct genl_info *info)
 
 	if (addr_l.id == 0) {
 		NL_SET_ERR_MSG_ATTR(info->extack, laddr, "missing local addr id");
+		err = -EINVAL;
 		goto create_err;
 	}
 
@@ -395,11 +397,13 @@ int mptcp_nl_cmd_sf_destroy(struct sk_buff *skb, struct genl_info *info)
 
 	if (addr_l.family != addr_r.family) {
 		GENL_SET_ERR_MSG(info, "address families do not match");
+		err = -EINVAL;
 		goto destroy_err;
 	}
 
 	if (!addr_l.port || !addr_r.port) {
 		GENL_SET_ERR_MSG(info, "missing local or remote port");
+		err = -EINVAL;
 		goto destroy_err;
 	}