[PATCH 1/1][T/X/B/C/D] cdrom: fix improper type cast, which can leat to information leak.

[Tyler Hicks]

From: Young_X <YangX92 at hotmail.com>

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 at hotmail.com>
Signed-off-by: Jens Axboe <axboe at kernel.dk>

CVE-2018-18710

(cherry picked from commit e4f3aa2e1e67bb48dfbaaf1cad59013d5a5bc276)
Signed-off-by: Tyler Hicks <tyhicks at canonical.com>
---
 drivers/cdrom/cdrom.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index 104cd4f7a2dd..7c2c520cc1b4 100644
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -2441,7 +2441,7 @@ static int cdrom_ioctl_select_disc(struct cdrom_device_info *cdi,
 		return -ENOSYS;
 
 	if (arg != CDSL_CURRENT && arg != CDSL_NONE) {
-		if ((int)arg >= cdi->capacity)
+		if (arg >= cdi->capacity)
 			return -EINVAL;
 	}
 
-- 
2.7.4