netlink: validate addr_len on bind

Otherwise an out of bounds read could happen.
Signed-off-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netlink/af_netlink.c

@@ -669,6 +669,9 @@ static int netlink_bind(struct socket *sock, struct sockaddr *addr,
 	struct sockaddr_nl *nladdr = (struct sockaddr_nl *)addr;
 	int err;
 
+	if (addr_len < sizeof(struct sockaddr_nl))
+		return -EINVAL;
+
 	if (nladdr->nl_family != AF_NETLINK)
 		return -EINVAL;