[PATCH 6.8 049/143] btrfs: export: handle invalid inode or root reference in btrfs_get_parent()

Greg Kroah-Hartman
2024-04-11T10:09:06Z

From: David Sterba <dsterba@suse.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@toxicpanda.com>
Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.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 63d4cc338b81a..1ac00ee7959b7 100644
--- a/fs/btrfs/export.c
+++ b/fs/btrfs/export.c
@@ -174,8 +174,15 @@ 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