[PATCH 5.4 132/191] md: make sure desc_nr less than MD_SB_DISKS

[Greg Kroah-Hartman]

From: Yufen Yu <yuyufen@xxxxxxxxxx>

[ Upstream commit 3b7436cc9449d5ff7fa1c1fd5bc3edb6402ff5b8 ]

For super_90_load, we need to make sure 'desc_nr' less
than MD_SB_DISKS, avoiding invalid memory access of 'sb->disks'.

Fixes: 228fc7d76db6 ("md: avoid invalid memory access for array sb->dev_roles")
Signed-off-by: Yufen Yu <yuyufen@xxxxxxxxxx>
Signed-off-by: Song Liu <songliubraving@xxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
---
 drivers/md/md.c |    1 +
 1 file changed, 1 insertion(+)

--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1159,6 +1159,7 @@ static int super_90_load(struct md_rdev
 	/* not spare disk, or LEVEL_MULTIPATH */
 	if (sb->level == LEVEL_MULTIPATH ||
 		(rdev->desc_nr >= 0 &&
+		 rdev->desc_nr < MD_SB_DISKS &&
 		 sb->disks[rdev->desc_nr].state &
 		 ((1<<MD_DISK_SYNC) | (1 << MD_DISK_ACTIVE))))
 		spare_disk = false;