[PATCH 4.19 18/48] btrfs: fix inode list leak during backref walking at resolve_indirect_refs()

[Greg Kroah-Hartman <gregkh@linuxfoundation.org>]

From: Filipe Manana <fdmanana@suse.com>

[ Upstream commit 5614dc3a47e3310fbc77ea3b67eaadd1c6417bf1 ]

During backref walking, at resolve_indirect_refs(), if we get an error
we jump to the 'out' label and call ulist_free() on the 'parents' ulist,
which frees all the elements in the ulist - however that does not free
any inode lists that may be attached to elements, through the 'aux' field
of a ulist node, so we end up leaking lists if we have any attached to
the unodes.

Fix this by calling free_leaf_list() instead of ulist_free() when we exit
from resolve_indirect_refs(). The static function free_leaf_list() is
moved up for this to be possible and it's slightly simplified by removing
unnecessary code.

Fixes: 3301958b7c1d ("Btrfs: add inodes before dropping the extent lock in find_all_leafs")
Signed-off-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: David Sterba <dsterba@suse.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 fs/btrfs/backref.c | 36 +++++++++++++++++-------------------
 1 file changed, 17 insertions(+), 19 deletions(-)

diff --git a/fs/btrfs/backref.c b/fs/btrfs/backref.c
index 781c725e6432..a1eb573fbb10 100644
--- a/fs/btrfs/backref.c
+++ b/fs/btrfs/backref.c
@@ -589,6 +589,18 @@ unode_aux_to_inode_list(struct ulist_node *node)
 	return (struct extent_inode_elem *)(uintptr_t)node->aux;
 }
 
+static void free_leaf_list(struct ulist *ulist)
+{
+	struct ulist_node *node;
+	struct ulist_iterator uiter;
+
+	ULIST_ITER_INIT(&uiter);
+	while ((node = ulist_next(ulist, &uiter)))
+		free_inode_elem_list(unode_aux_to_inode_list(node));
+
+	ulist_free(ulist);
+}
+
 /*
  * We maintain three seperate rbtrees: one for direct refs, one for
  * indirect refs which have a key, and one for indirect refs which do not
@@ -703,7 +715,11 @@ static int resolve_indirect_refs(struct btrfs_fs_info *fs_info,
 		cond_resched();
 	}
 out:
-	ulist_free(parents);
+	/*
+	 * We may have inode lists attached to refs in the parents ulist, so we
+	 * must free them before freeing the ulist and its refs.
+	 */
+	free_leaf_list(parents);
 	return ret;
 }
 
@@ -1360,24 +1376,6 @@ static int find_parent_nodes(struct btrfs_trans_handle *trans,
 	return ret;
 }
 
-static void free_leaf_list(struct ulist *blocks)
-{
-	struct ulist_node *node = NULL;
-	struct extent_inode_elem *eie;
-	struct ulist_iterator uiter;
-
-	ULIST_ITER_INIT(&uiter);
-	while ((node = ulist_next(blocks, &uiter))) {
-		if (!node->aux)
-			continue;
-		eie = unode_aux_to_inode_list(node);
-		free_inode_elem_list(eie);
-		node->aux = 0;
-	}
-
-	ulist_free(blocks);
-}
-
 /*
  * Finds all leafs with a reference to the specified combination of bytenr and
  * offset. key_list_head will point to a list of corresponding keys (caller must
-- 
2.35.1