cdrom: fix improper type cast, which can leat to information leak.

There is another cast from unsigned long to int which causes
a bounds check to fail with specially crafted input. The value is
then used as an index in the slot array in cdrom_slot_status().

This issue is similar to CVE-2018-16658 and CVE-2018-10940.

Signed-off-by: Young_X <YangX92@hotmail.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
int cdrom_mode_sense(struct cdrom_device_info *cdi,
		     struct packet_command *cgc,
		     int page_code, int page_control)
{
	const struct cdrom_device_ops *cdo = cdi->ops;

	memset(cgc->cmd, 0, sizeof(cgc->cmd));

	cgc->cmd[0] = GPCMD_MODE_SENSE_10;
	cgc->cmd[2] = page_code | (page_control << 6);
	cgc->cmd[7] = cgc->buflen >> 8;
	cgc->cmd[8] = cgc->buflen & 0xff;
	cgc->data_direction = CGC_DATA_READ;
	return cdo->generic_packet(cdi, cgc);
}

int cdrom_mode_sense(struct cdrom_device_info *cdi,
		     struct packet_command *cgc,
		     int page_code, int page_control)
{
	const struct cdrom_device_ops *cdo = cdi->ops;

	memset(cgc->cmd, 0, sizeof(cgc->cmd));

	cgc->cmd[0] = GPCMD_MODE_SENSE_10;
	cgc->cmd[2] = page_code | (page_control << 6);
	cgc->cmd[7] = cgc->buflen >> 8;
	cgc->cmd[8] = cgc->buflen & 0xff;
	cgc->data_direction = CGC_DATA_READ;
	return cdo->generic_packet(cdi, cgc);
}
