can: isotp: isotp_getname(): fix kernel information leak

Initialize the sockaddr_can structure to prevent a data leak to user space.

Suggested-by: Cong Wang <xiyou.wangcong@gmail.com>
Reported-by:  <syzbot+057884e2f453e8afebc8@syzkaller.appspotmail.com>
Fixes: e057dd3f ("can: add ISO 15765-2:2016 transport protocol")
Signed-off-by: Oliver Hartkopp <socketcan@hartkopp.net>
Link: https://lore.kernel.org/r/20210112091643.11789-1-socketcan@hartkopp.net


Signed-off-by: Marc Kleine-Budde <mkl@pengutronix.de>

net/can/isotp.c

@@ -1155,6 +1155,7 @@ static int isotp_getname(struct socket *sock, struct sockaddr *uaddr, int peer)
 	if (peer)
 		return -EOPNOTSUPP;
 
+	memset(addr, 0, sizeof(*addr));
 	addr->can_family = AF_CAN;
 	addr->can_ifindex = so->ifindex;
 	addr->can_addr.tp.rx_id = so->rxid;