linux-kernel - [PATCH AUTOSEL 4.19 09/11] btrfs: export: handle invalid inode or root reference in btrfs_get

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Date: Fri, 29 Mar 2024 08:35:15 -0400
From: Sasha Levin <sashal@...nel.org>
To: linux-kernel@...r.kernel.org,
	stable@...r.kernel.org
Cc: David Sterba <dsterba@...e.com>,
	Josef Bacik <josef@...icpanda.com>,
	Anand Jain <anand.jain@...cle.com>,
	Sasha Levin <sashal@...nel.org>,
	clm@...com,
	linux-btrfs@...r.kernel.org
Subject: [PATCH AUTOSEL 4.19 09/11] btrfs: export: handle invalid inode or root reference in btrfs_get_parent()

From: David Sterba <dsterba@...e.com>

[ Upstream commit 26b66d1d366a375745755ca7365f67110bbf6bd5 ]

The get_parent handler looks up a parent of a given dentry, this can be
either a subvolume or a directory. The search is set up with offset -1
but it's never expected to find such item, as it would break allowed
range of inode number or a root id. This means it's a corruption (ext4
also returns this error code).

Reviewed-by: Josef Bacik <josef@...icpanda.com>
Reviewed-by: Anand Jain <anand.jain@...cle.com>
Signed-off-by: David Sterba <dsterba@...e.com>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 fs/btrfs/export.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/export.c b/fs/btrfs/export.c
index ecc33e3a3c063..01e9a5afc33bf 100644
--- a/fs/btrfs/export.c
+++ b/fs/btrfs/export.c
@@ -182,8 +182,15 @@ struct dentry *btrfs_get_parent(struct dentry *child)
 	ret = btrfs_search_slot(NULL, root, &key, path, 0, 0);
 	if (ret < 0)
 		goto fail;
+	if (ret == 0) {
+		/*
+		 * Key with offset of -1 found, there would have to exist an
+		 * inode with such number or a root with such id.
+		 */
+		ret = -EUCLEAN;
+		goto fail;
+	}
 
-	BUG_ON(ret == 0); /* Key with offset of -1 found */
 	if (path->slots[0] == 0) {
 		ret = -ENOENT;
 		goto fail;
-- 
2.43.0