md: avoid array overflow with bad v1.x metadata



We trust the 'desc_nr' field in v1.x metadata enough to use it
as an index in an array.  This isn't really safe.
So range-check the value first.

Signed-off-by: NeilBrown <neilb@suse.de>

parent 3a981b03

drivers/md/md.c

+6 −1

Original line number	Diff line number	Diff line
		@@ -1308,6 +1308,11 @@ static int super_1_validate(mddev_t mddev, mdk_rdev_t rdev)
		}
		if (mddev->level != LEVEL_MULTIPATH) {
		int role;
		if (rdev->desc_nr < 0 \|\|
		rdev->desc_nr >= le32_to_cpu(sb->max_dev)) {
		role = 0xffff;
		rdev->desc_nr = -1;
		} else
		role = le16_to_cpu(sb->dev_roles[rdev->desc_nr]);
		switch(role) {
		case 0xffff: /* spare */