Language: Go
Label: vulnerable
CWE: CWE-400 \u2014 Uncontrolled Resource Consumption
The product does not properly control the allocation and maintenance of a limited resource, thereby enabling an actor to influence the amount of resources consumed, eventually leading to the exhaustion of available resources.

Code:
func (s *shard) serialize(ls *ipld.LinkSystem) (ipld.Link, uint64, error) {
	ufd, err := BuildUnixFS(func(b *Builder) {
		DataType(b, data.Data_HAMTShard)
		HashType(b, s.hasher)
		Data(b, s.bitmap())
		Fanout(b, uint64(s.size))
	})
	if err != nil {
		return nil, 0, err
	}
	pbb := dagpb.Type.PBNode.NewBuilder()
	pbm, err := pbb.BeginMap(2)
	if err != nil {
		return nil, 0, err
	}
	if err = pbm.AssembleKey().AssignString("Data"); err != nil {
		return nil, 0, err
	}
	if err = pbm.AssembleValue().AssignBytes(data.EncodeUnixFSData(ufd)); err != nil {
		return nil, 0, err
	}
	if err = pbm.AssembleKey().AssignString("Links"); err != nil {
		return nil, 0, err
	}

	lnkBuilder := dagpb.Type.PBLinks.NewBuilder()
	lnks, err := lnkBuilder.BeginList(int64(len(s.children)))
	if err != nil {
		return nil, 0, err
	}
	// sorting happens in codec-dagpb
	var totalSize uint64
	for idx, e := range s.children {
		var lnk dagpb.PBLink
		if e.shard != nil {
			ipldLnk, sz, err := e.shard.serialize(ls)
			if err != nil {
				return nil, 0, err
			}
			totalSize += sz
			fullName := s.formatLinkName("", idx)
			lnk, err = BuildUnixFSDirectoryEntry(fullName, int64(sz), ipldLnk)
			if err != nil {
				return nil, 0, err
			}
		} else {
			fullName := s.formatLinkName(e.Name.Must().String(), idx)
			sz := e.Tsize.Must().Int()
			totalSize += uint64(sz)
			lnk, err = BuildUnixFSDirectoryEntry(fullName, sz, e.Hash.Link())
		}
		if err != nil {
			return nil, 0, err
		}
		if err := lnks.AssembleValue().AssignNode(lnk); err != nil {
			return nil, 0, err
		}
	}
	if err := lnks.Finish(); err != nil {
		return nil, 0, err
	}
	pbm.AssembleValue().AssignNode(lnkBuilder.Build())
	if err := pbm.Finish(); err != nil {
		return nil, 0, err
	}
	node := pbb.Build()
	lnk, sz, err := sizedStore(ls, fileLinkProto, node)
	if err != nil {
		return nil, 0, err
	}
	return lnk, totalSize + sz, nil
}