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

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>

diff --git a/drivers/cdrom/cdrom.c b/drivers/cdrom/cdrom.c
index 8cfa10a..930b496 100644 (file)
--- 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;
        }