Bluetooth: bnep: fix buffer overflow

Struct ca is copied from userspace.  It is not checked whether the "device"
field is NULL terminated.  This potentially leads to BUG() inside of
alloc_netdev_mqs() and/or information leak by creating a device with a name
made of contents of kernel stack.
Signed-off-by: NVasiliy Kulikov <segoon@openwall.com>
Signed-off-by: NGustavo F. Padovan <padovan@profusion.mobi>

net/bluetooth/bnep/sock.c

@@ -88,6 +88,7 @@ static int bnep_sock_ioctl(struct socket *sock, unsigned int cmd, unsigned long
 			sockfd_put(nsock);
 			return -EBADFD;
 		}
+		ca.device[sizeof(ca.device)-1] = 0;
 
 		err = bnep_add_connection(&ca, nsock);
 		if (!err) {