release/5.2.37/btrfs-do-not-delete-mismatched-root-refs.patch

From d67254a7a00e2627de55455001a51e6c1593c700 Mon Sep 17 00:00:00 2001
From: Josef Bacik <josef@toxicpanda.com>
Date: Wed, 18 Dec 2019 17:20:29 -0500
Subject: [PATCH] btrfs: do not delete mismatched root refs

commit 423a716cd7be16fb08690760691befe3be97d3fc upstream.

btrfs_del_root_ref() will simply WARN_ON() if the ref doesn't match in
any way, and then continue to delete the reference.  This shouldn't
happen, we have these values because there's more to the reference than
the original root and the sub root.  If any of these checks fail, return
-ENOENT.

CC: stable@vger.kernel.org # 4.4+
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: David Sterba <dsterba@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/fs/btrfs/root-tree.c b/fs/btrfs/root-tree.c
index 22124122728c..24a581030840 100644
--- a/fs/btrfs/root-tree.c
+++ b/fs/btrfs/root-tree.c
@@ -374,11 +374,13 @@ int btrfs_del_root_ref(struct btrfs_trans_handle *trans, u64 root_id,
 		leaf = path->nodes[0];
 		ref = btrfs_item_ptr(leaf, path->slots[0],
 				     struct btrfs_root_ref);
-
-		WARN_ON(btrfs_root_ref_dirid(leaf, ref) != dirid);
-		WARN_ON(btrfs_root_ref_name_len(leaf, ref) != name_len);
 		ptr = (unsigned long)(ref + 1);
-		WARN_ON(memcmp_extent_buffer(leaf, name, ptr, name_len));
+		if ((btrfs_root_ref_dirid(leaf, ref) != dirid) ||
+		    (btrfs_root_ref_name_len(leaf, ref) != name_len) ||
+		    memcmp_extent_buffer(leaf, name, ptr, name_len)) {
+			err = -ENOENT;
+			goto out;
+		}
 		*sequence = btrfs_root_ref_sequence(leaf, ref);
 
 		ret = btrfs_del_item(trans, tree_root, path);
-- 
2.7.4