From: NeilBrown <neilb@suse.de>
Date: Mon, 3 Aug 2009 00:59:56 +0000 (+1000)
Subject: md: avoid array overflow with bad v1.x metadata
X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=3673f305faf1bc66ead751344f8262ace851ff44;p=GitHub%2FLineageOS%2Fandroid_kernel_samsung_universal7580.git

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>
---

diff --git a/drivers/md/md.c b/drivers/md/md.c
index c194955aeca..249b2896d4e 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -1308,7 +1308,12 @@ static int super_1_validate(mddev_t *mddev, mdk_rdev_t *rdev)
 	}
 	if (mddev->level != LEVEL_MULTIPATH) {
 		int role;
-		role = le16_to_cpu(sb->dev_roles[rdev->desc_nr]);
+		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 */
 			break;