[PATCH 5.10 09/84] dm raid: fix KASAN warning in raid5_add_disks

[Greg Kroah-Hartman]

From: Mikulas Patocka <mpatocka@xxxxxxxxxx>

commit 617b365872a247480e9dcd50a32c8d1806b21861 upstream.

There's a KASAN warning in raid5_add_disk when running the LVM testsuite.
The warning happens in the test
lvconvert-raid-reshape-linear_to_raid6-single-type.sh. We fix the warning
by verifying that rdev->saved_raid_disk is within limits.

Cc: stable@xxxxxxxxxxxxxxx
Signed-off-by: Mikulas Patocka <mpatocka@xxxxxxxxxx>
Signed-off-by: Mike Snitzer <snitzer@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/md/raid5.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -8004,6 +8004,7 @@ static int raid5_add_disk(struct mddev *
 	 */
 	if (rdev->saved_raid_disk >= 0 &&
 	    rdev->saved_raid_disk >= first &&
+	    rdev->saved_raid_disk <= last &&
 	    conf->disks[rdev->saved_raid_disk].rdev == NULL)
 		first = rdev->saved_raid_disk;