From e4f3aa2e1e67bb48dfbaaf1cad59013d5a5bc276 Mon Sep 17 00:00:00 2001
From: Young_X <YangX92@hotmail.com>
Date: Wed, 3 Oct 2018 12:54:29 +0000
Subject: cdrom: fix improper type cast, which can leat to information leak.

From: Young_X <YangX92@hotmail.com>

commit e4f3aa2e1e67bb48dfbaaf1cad59013d5a5bc276 upstream.

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>
Cc: Ben Hutchings <ben.hutchings@codethink.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/cdrom/cdrom.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -2445,7 +2445,7 @@ static int cdrom_ioctl_select_disc(struc
 		return -ENOSYS;
 
 	if (arg != CDSL_CURRENT && arg != CDSL_NONE) {
-		if ((int)arg >= cdi->capacity)
+		if (arg >= cdi->capacity)
 			return -EINVAL;
 	}