linux-kernel - [PATCH 4.14 12/45] dm btree remove: fix use after free in rebalance

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Message-Id: <20211220143022.678962718@linuxfoundation.org>
Date:   Mon, 20 Dec 2021 15:34:07 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Joe Thornber <ejt@...hat.com>,
        Mike Snitzer <snitzer@...hat.com>
Subject: [PATCH 4.14 12/45] dm btree remove: fix use after free in rebalance_children()

From: Joe Thornber <ejt@...hat.com>

commit 1b8d2789dad0005fd5e7d35dab26a8e1203fb6da upstream.

Move dm_tm_unlock() after dm_tm_dec().

Cc: stable@...r.kernel.org
Signed-off-by: Joe Thornber <ejt@...hat.com>
Signed-off-by: Mike Snitzer <snitzer@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 drivers/md/persistent-data/dm-btree-remove.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/md/persistent-data/dm-btree-remove.c
+++ b/drivers/md/persistent-data/dm-btree-remove.c
@@ -423,9 +423,9 @@ static int rebalance_children(struct sha
 
 		memcpy(n, dm_block_data(child),
 		       dm_bm_block_size(dm_tm_get_bm(info->tm)));
-		dm_tm_unlock(info->tm, child);
 
 		dm_tm_dec(info->tm, dm_block_location(child));
+		dm_tm_unlock(info->tm, child);
 		return 0;
 	}