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>
(cherry picked from commit e4f3aa2e1e67bb48dfbaaf1cad59013d5a5bc276)

Orabug: 28929767
CVE: CVE-2018-18710

Reviewed-by: Darren Kenny <darren.kenny@oracle.com>
Signed-off-by: Allen Pais <allen.pais@oracle.com>
Signed-off-by: Brian Maly <brian.maly@oracle.com>

diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index 39e65eb3dcf0d90a20f8d5dd0f50dd9fb638d264..2411edf92fe503fef61fd8088277b4301dc748e2 100644 (file)
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -2427,7 +2427,7 @@ 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;
        }