net: tipc: fix information leak to userland

commit 88f8a5e3 upstream.

Structure sockaddr_tipc is copied to userland with padding bytes after
"id" field in union field "name" unitialized.  It leads to leaking of
contents of kernel stack memory.  We have to initialize them to zero.
Signed-off-by: Vasiliy Kulikov <segooon@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Cc: Moritz Muehlenhoff <jmm@debian.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

net/tipc/socket.c

@@ -393,6 +393,7 @@ static int get_name(struct socket *sock, struct sockaddr *uaddr,
 	struct sockaddr_tipc *addr = (struct sockaddr_tipc *)uaddr;
 	struct tipc_sock *tsock = tipc_sk(sock->sk);
 
+	memset(addr, 0, sizeof(*addr));
 	if (peer) {
 		if ((sock->state != SS_CONNECTED) &&
 			((peer != 2) || (sock->state != SS_DISCONNECTING)))