selinux: Check address length before reading address family

KMSAN will complain if valid address length passed to bind()/connect() is
shorter than sizeof("struct sockaddr"->sa_family) bytes.
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Paul Moore <paul@paul-moore.com>

security/selinux/hooks.c

@@ -4512,7 +4512,7 @@ static int selinux_socket_bind(struct socket *sock, struct sockaddr *address, in
 		struct lsm_network_audit net = {0,};
 		struct sockaddr_in *addr4 = NULL;
 		struct sockaddr_in6 *addr6 = NULL;
-		u16 family_sa = address->sa_family;
+		u16 family_sa;
 		unsigned short snum;
 		u32 sid, node_perm;
 
@@ -4522,6 +4522,9 @@ static int selinux_socket_bind(struct socket *sock, struct sockaddr *address, in
 		 * need to check address->sa_family as it is possible to have
 		 * sk->sk_family = PF_INET6 with addr->sa_family = AF_INET.
 		 */
+		if (addrlen < offsetofend(struct sockaddr, sa_family))
+			return -EINVAL;
+		family_sa = address->sa_family;
 		switch (family_sa) {
 		case AF_UNSPEC:
 		case AF_INET:
@@ -4654,6 +4657,8 @@ static int selinux_socket_connect_helper(struct socket *sock,
 		 * need to check address->sa_family as it is possible to have
 		 * sk->sk_family = PF_INET6 with addr->sa_family = AF_INET.
 		 */
+		if (addrlen < offsetofend(struct sockaddr, sa_family))
+			return -EINVAL;
 		switch (address->sa_family) {
 		case AF_INET:
 			addr4 = (struct sockaddr_in *)address;