btrfs: fix leak of path in btrfs_find_item

If btrfs_find_item is called with NULL path it allocates one locally but
does not free it. Affected paths are inserting an orphan item for a file
and for a subvol root.

Move the path allocation to the callers.

CC: <[e-mail]> # 3.14+
Fixes: 3f870c289900 ("btrfs: expand btrfs_find_item() to include find_orphan_item functionality")
Signed-off-by: David Sterba <[e-mail]>

fs/btrfs/ctree.c

···
 	return 0;
 }
 
-int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *found_path,
+int btrfs_find_item(struct btrfs_root *fs_root, struct btrfs_path *path,
 		u64 iobjectid, u64 ioff, u8 key_type,
 		struct btrfs_key *found_key)
 {
 	int ret;
 	struct btrfs_key key;
 	struct extent_buffer *eb;
-	struct btrfs_path *path;
+
+	ASSERT(path);
 
 	key.type = key_type;
 	key.objectid = iobjectid;
 	key.offset = ioff;
 
-	if (found_path == NULL) {
-		path = btrfs_alloc_path();
-		if (!path)
-			return -ENOMEM;
-	} else
-		path = found_path;
-
 	ret = btrfs_search_slot(NULL, fs_root, &key, path, 0, 0);
-	if ((ret < 0) || (found_key == NULL)) {
-		if (path != found_path)
-			btrfs_free_path(path);
+	if ((ret < 0) || (found_key == NULL))
 		return ret;
-	}
 
 	eb = path->nodes[0];
 	if (ret && path->slots[0] >= btrfs_header_nritems(eb)) {

fs/btrfs/disk-io.c

···
 				     bool check_ref)
 {
 	struct btrfs_root *root;
+	struct btrfs_path *path;
 	int ret;
 
 	if (location->objectid == BTRFS_ROOT_TREE_OBJECTID)
···
 	if (ret)
 		goto fail;
 
-	ret = btrfs_find_item(fs_info->tree_root, NULL, BTRFS_ORPHAN_OBJECTID,
+	path = btrfs_alloc_path();
+	if (!path) {
+		ret = -ENOMEM;
+		goto fail;
+	}
+	ret = btrfs_find_item(fs_info->tree_root, path, BTRFS_ORPHAN_OBJECTID,
 			location->objectid, BTRFS_ORPHAN_ITEM_KEY, NULL);
+	btrfs_free_path(path);
 	if (ret < 0)
 		goto fail;
 	if (ret == 0)

fs/btrfs/tree-log.c

···
 			      struct btrfs_root *root, u64 offset)
 {
 	int ret;
-	ret = btrfs_find_item(root, NULL, BTRFS_ORPHAN_OBJECTID,
+	struct btrfs_path *path;
+
+	path = btrfs_alloc_path();
+	if (!path)
+		return -ENOMEM;
+
+	ret = btrfs_find_item(root, path, BTRFS_ORPHAN_OBJECTID,
 			offset, BTRFS_ORPHAN_ITEM_KEY, NULL);
 	if (ret > 0)
 		ret = btrfs_insert_orphan_item(trans, root, offset);
+
+	btrfs_free_path(path);
+
 	return ret;
 }