[PATCH 05/14] btrfs: handle invalid root reference found in may_destroy_subvol()

[David Sterba <dsterba@suse.com>]

The may_destroy_subvol() looks up a root by a key, allowing to do an
inexact search when key->offset is -1.  It's never expected to find such
item, as it would break the allowed range of a root id.

Signed-off-by: David Sterba <dsterba@suse.com>
---
 fs/btrfs/inode.c | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 311d252addaf..0b36dfb6754b 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -4389,7 +4389,14 @@ static noinline int may_destroy_subvol(struct btrfs_root *root)
 	ret = btrfs_search_slot(NULL, fs_info->tree_root, &key, path, 0, 0);
 	if (ret < 0)
 		goto out;
-	BUG_ON(ret == 0);
+	if (ret == 0) {
+		/*
+		 * Key with offset -1 found, there would have to exist a root
+		 * with such id, but this is out of valid range.
+		 */
+		ret = -EUCLEAN;
+		goto out;
+	}
 
 	ret = 0;
 	if (path->slots[0] > 0) {
-- 
2.42.1