linux-kernel - [PATCH] btrfs: avoid use-after-free when return the error code

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Date:   Wed, 23 Nov 2022 22:39:45 +0800
From:   void0red <void0red@...il.com>
To:     dsterba@...e.com
Cc:     linux-btrfs@...r.kernel.org, linux-kernel@...r.kernel.org,
        void0red <void0red@...il.com>, eriri <1527030098@...com>
Subject: [PATCH] btrfs: avoid use-after-free when return the error code

free_extent_map(em) will free em->map_lookup, so it is
wrong to use it when return.

Link: https://bugzilla.kernel.org/show_bug.cgi?id=216721
Signed-off-by: void0red <void0red@...il.com>
Reported-by: eriri <1527030098@...com>
---
 fs/btrfs/volumes.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c
index 635f45f1a2ef..dba087ad40ea 100644
--- a/fs/btrfs/volumes.c
+++ b/fs/btrfs/volumes.c
@@ -7241,8 +7241,9 @@ static int read_one_chunk(struct btrfs_key *key, struct extent_buffer *leaf,
 			map->stripes[i].dev = handle_missing_device(fs_info,
 								    devid, uuid);
 			if (IS_ERR(map->stripes[i].dev)) {
+				ret = PTR_ERR(map->stripes[i].dev);
 				free_extent_map(em);
-				return PTR_ERR(map->stripes[i].dev);
+				return ret;
 			}
 		}
 
-- 
2.34.1