cdrom: Fix info leak/OOB read in cdrom_ioctl_drive_status

Like d88b6d04: "cdrom: information leak in cdrom_ioctl_media_changed()"

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().

Signed-off-by: Scott Bauer <scott.bauer@intel.com>
Signed-off-by: Scott Bauer <sbauer@plzdonthack.me>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@kernel.dk>
(cherry picked from commit 8f3fafc9c2f0ece10832c25f7ffcb07c97a32ad4)

Orabug: 28664501
CVE: CVE-2018-16658

Reviewed-by: Jack Vogel <jack.vogel@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 5d28a45d2960c6a40945b134c755ff03a1117c76..39e65eb3dcf0d90a20f8d5dd0f50dd9fb638d264 100644 (file)
--- a/drivers/cdrom/cdrom.c
+++ b/drivers/cdrom/cdrom.c
@@ -2528,7 +2528,7 @@ static int cdrom_ioctl_drive_status(struct cdrom_device_info *cdi,
        if (!CDROM_CAN(CDC_SELECT_DISC) ||
            (arg == CDSL_CURRENT || arg == CDSL_NONE))
                return cdi->ops->drive_status(cdi, CDSL_CURRENT);
-       if (((int)arg >= cdi->capacity))
+       if (arg >= cdi->capacity)
                return -EINVAL;
        return cdrom_slot_status(cdi, arg);
 }