core/state: fix runaway alloc caused by prefetcher heap escape (#30629)

Co-authored-by: lightclient <lightclient@protonmail.com>
This commit is contained in:
Péter Szilágyi 2024-10-20 13:25:15 +03:00 committed by GitHub
parent b6c62d5887
commit babd5d8026
No known key found for this signature in database
GPG Key ID: B5690EEEBB952194
4 changed files with 115 additions and 77 deletions

@ -199,7 +199,7 @@ func (s *stateObject) GetCommittedState(key common.Hash) common.Hash {
// Schedule the resolved storage slots for prefetching if it's enabled. // Schedule the resolved storage slots for prefetching if it's enabled.
if s.db.prefetcher != nil && s.data.Root != types.EmptyRootHash { if s.db.prefetcher != nil && s.data.Root != types.EmptyRootHash {
if err = s.db.prefetcher.prefetch(s.addrHash, s.origin.Root, s.address, [][]byte{key[:]}, true); err != nil { if err = s.db.prefetcher.prefetch(s.addrHash, s.origin.Root, s.address, nil, []common.Hash{key}, true); err != nil {
log.Error("Failed to prefetch storage slot", "addr", s.address, "key", key, "err", err) log.Error("Failed to prefetch storage slot", "addr", s.address, "key", key, "err", err)
} }
} }
@ -237,7 +237,7 @@ func (s *stateObject) setState(key common.Hash, value common.Hash, origin common
// finalise moves all dirty storage slots into the pending area to be hashed or // finalise moves all dirty storage slots into the pending area to be hashed or
// committed later. It is invoked at the end of every transaction. // committed later. It is invoked at the end of every transaction.
func (s *stateObject) finalise() { func (s *stateObject) finalise() {
slotsToPrefetch := make([][]byte, 0, len(s.dirtyStorage)) slotsToPrefetch := make([]common.Hash, 0, len(s.dirtyStorage))
for key, value := range s.dirtyStorage { for key, value := range s.dirtyStorage {
if origin, exist := s.uncommittedStorage[key]; exist && origin == value { if origin, exist := s.uncommittedStorage[key]; exist && origin == value {
// The slot is reverted to its original value, delete the entry // The slot is reverted to its original value, delete the entry
@ -250,7 +250,7 @@ func (s *stateObject) finalise() {
// The slot is different from its original value and hasn't been // The slot is different from its original value and hasn't been
// tracked for commit yet. // tracked for commit yet.
s.uncommittedStorage[key] = s.GetCommittedState(key) s.uncommittedStorage[key] = s.GetCommittedState(key)
slotsToPrefetch = append(slotsToPrefetch, common.CopyBytes(key[:])) // Copy needed for closure slotsToPrefetch = append(slotsToPrefetch, key) // Copy needed for closure
} }
// Aggregate the dirty storage slots into the pending area. It might // Aggregate the dirty storage slots into the pending area. It might
// be possible that the value of tracked slot here is same with the // be possible that the value of tracked slot here is same with the
@ -261,7 +261,7 @@ func (s *stateObject) finalise() {
s.pendingStorage[key] = value s.pendingStorage[key] = value
} }
if s.db.prefetcher != nil && len(slotsToPrefetch) > 0 && s.data.Root != types.EmptyRootHash { if s.db.prefetcher != nil && len(slotsToPrefetch) > 0 && s.data.Root != types.EmptyRootHash {
if err := s.db.prefetcher.prefetch(s.addrHash, s.data.Root, s.address, slotsToPrefetch, false); err != nil { if err := s.db.prefetcher.prefetch(s.addrHash, s.data.Root, s.address, nil, slotsToPrefetch, false); err != nil {
log.Error("Failed to prefetch slots", "addr", s.address, "slots", len(slotsToPrefetch), "err", err) log.Error("Failed to prefetch slots", "addr", s.address, "slots", len(slotsToPrefetch), "err", err)
} }
} }
@ -323,7 +323,7 @@ func (s *stateObject) updateTrie() (Trie, error) {
// Whereas if the created node is handled first, then the collapse is avoided, and `B` is not resolved. // Whereas if the created node is handled first, then the collapse is avoided, and `B` is not resolved.
var ( var (
deletions []common.Hash deletions []common.Hash
used = make([][]byte, 0, len(s.uncommittedStorage)) used = make([]common.Hash, 0, len(s.uncommittedStorage))
) )
for key, origin := range s.uncommittedStorage { for key, origin := range s.uncommittedStorage {
// Skip noop changes, persist actual changes // Skip noop changes, persist actual changes
@ -346,7 +346,7 @@ func (s *stateObject) updateTrie() (Trie, error) {
deletions = append(deletions, key) deletions = append(deletions, key)
} }
// Cache the items for preloading // Cache the items for preloading
used = append(used, common.CopyBytes(key[:])) // Copy needed for closure used = append(used, key) // Copy needed for closure
} }
for _, key := range deletions { for _, key := range deletions {
if err := tr.DeleteStorage(s.address, key[:]); err != nil { if err := tr.DeleteStorage(s.address, key[:]); err != nil {
@ -356,7 +356,7 @@ func (s *stateObject) updateTrie() (Trie, error) {
s.db.StorageDeleted.Add(1) s.db.StorageDeleted.Add(1)
} }
if s.db.prefetcher != nil { if s.db.prefetcher != nil {
s.db.prefetcher.used(s.addrHash, s.data.Root, used) s.db.prefetcher.used(s.addrHash, s.data.Root, nil, used)
} }
s.uncommittedStorage = make(Storage) // empties the commit markers s.uncommittedStorage = make(Storage) // empties the commit markers
return tr, nil return tr, nil

@ -214,7 +214,7 @@ func (s *StateDB) StartPrefetcher(namespace string, witness *stateless.Witness)
// the prefetcher is constructed. For more details, see: // the prefetcher is constructed. For more details, see:
// https://github.com/ethereum/go-ethereum/issues/29880 // https://github.com/ethereum/go-ethereum/issues/29880
s.prefetcher = newTriePrefetcher(s.db, s.originalRoot, namespace, witness == nil) s.prefetcher = newTriePrefetcher(s.db, s.originalRoot, namespace, witness == nil)
if err := s.prefetcher.prefetch(common.Hash{}, s.originalRoot, common.Address{}, nil, false); err != nil { if err := s.prefetcher.prefetch(common.Hash{}, s.originalRoot, common.Address{}, nil, nil, false); err != nil {
log.Error("Failed to prefetch account trie", "root", s.originalRoot, "err", err) log.Error("Failed to prefetch account trie", "root", s.originalRoot, "err", err)
} }
} }
@ -587,7 +587,7 @@ func (s *StateDB) getStateObject(addr common.Address) *stateObject {
} }
// Schedule the resolved account for prefetching if it's enabled. // Schedule the resolved account for prefetching if it's enabled.
if s.prefetcher != nil { if s.prefetcher != nil {
if err := s.prefetcher.prefetch(common.Hash{}, s.originalRoot, common.Address{}, [][]byte{addr[:]}, true); err != nil { if err = s.prefetcher.prefetch(common.Hash{}, s.originalRoot, common.Address{}, []common.Address{addr}, nil, true); err != nil {
log.Error("Failed to prefetch account", "addr", addr, "err", err) log.Error("Failed to prefetch account", "addr", addr, "err", err)
} }
} }
@ -720,7 +720,7 @@ func (s *StateDB) GetRefund() uint64 {
// the journal as well as the refunds. Finalise, however, will not push any updates // the journal as well as the refunds. Finalise, however, will not push any updates
// into the tries just yet. Only IntermediateRoot or Commit will do that. // into the tries just yet. Only IntermediateRoot or Commit will do that.
func (s *StateDB) Finalise(deleteEmptyObjects bool) { func (s *StateDB) Finalise(deleteEmptyObjects bool) {
addressesToPrefetch := make([][]byte, 0, len(s.journal.dirties)) addressesToPrefetch := make([]common.Address, 0, len(s.journal.dirties))
for addr := range s.journal.dirties { for addr := range s.journal.dirties {
obj, exist := s.stateObjects[addr] obj, exist := s.stateObjects[addr]
if !exist { if !exist {
@ -753,10 +753,10 @@ func (s *StateDB) Finalise(deleteEmptyObjects bool) {
// At this point, also ship the address off to the precacher. The precacher // At this point, also ship the address off to the precacher. The precacher
// will start loading tries, and when the change is eventually committed, // will start loading tries, and when the change is eventually committed,
// the commit-phase will be a lot faster // the commit-phase will be a lot faster
addressesToPrefetch = append(addressesToPrefetch, common.CopyBytes(addr[:])) // Copy needed for closure addressesToPrefetch = append(addressesToPrefetch, addr) // Copy needed for closure
} }
if s.prefetcher != nil && len(addressesToPrefetch) > 0 { if s.prefetcher != nil && len(addressesToPrefetch) > 0 {
if err := s.prefetcher.prefetch(common.Hash{}, s.originalRoot, common.Address{}, addressesToPrefetch, false); err != nil { if err := s.prefetcher.prefetch(common.Hash{}, s.originalRoot, common.Address{}, addressesToPrefetch, nil, false); err != nil {
log.Error("Failed to prefetch addresses", "addresses", len(addressesToPrefetch), "err", err) log.Error("Failed to prefetch addresses", "addresses", len(addressesToPrefetch), "err", err)
} }
} }
@ -877,7 +877,7 @@ func (s *StateDB) IntermediateRoot(deleteEmptyObjects bool) common.Hash {
// into a shortnode. This requires `B` to be resolved from disk. // into a shortnode. This requires `B` to be resolved from disk.
// Whereas if the created node is handled first, then the collapse is avoided, and `B` is not resolved. // Whereas if the created node is handled first, then the collapse is avoided, and `B` is not resolved.
var ( var (
usedAddrs [][]byte usedAddrs []common.Address
deletedAddrs []common.Address deletedAddrs []common.Address
) )
for addr, op := range s.mutations { for addr, op := range s.mutations {
@ -892,7 +892,7 @@ func (s *StateDB) IntermediateRoot(deleteEmptyObjects bool) common.Hash {
s.updateStateObject(s.stateObjects[addr]) s.updateStateObject(s.stateObjects[addr])
s.AccountUpdated += 1 s.AccountUpdated += 1
} }
usedAddrs = append(usedAddrs, common.CopyBytes(addr[:])) // Copy needed for closure usedAddrs = append(usedAddrs, addr) // Copy needed for closure
} }
for _, deletedAddr := range deletedAddrs { for _, deletedAddr := range deletedAddrs {
s.deleteStateObject(deletedAddr) s.deleteStateObject(deletedAddr)
@ -901,7 +901,7 @@ func (s *StateDB) IntermediateRoot(deleteEmptyObjects bool) common.Hash {
s.AccountUpdates += time.Since(start) s.AccountUpdates += time.Since(start)
if s.prefetcher != nil { if s.prefetcher != nil {
s.prefetcher.used(common.Hash{}, s.originalRoot, usedAddrs) s.prefetcher.used(common.Hash{}, s.originalRoot, usedAddrs, nil)
} }
// Track the amount of time wasted on hashing the account trie // Track the amount of time wasted on hashing the account trie
defer func(start time.Time) { s.AccountHashes += time.Since(start) }(time.Now()) defer func(start time.Time) { s.AccountHashes += time.Since(start) }(time.Now())

@ -118,31 +118,31 @@ func (p *triePrefetcher) report() {
fetcher.wait() // ensure the fetcher's idle before poking in its internals fetcher.wait() // ensure the fetcher's idle before poking in its internals
if fetcher.root == p.root { if fetcher.root == p.root {
p.accountLoadReadMeter.Mark(int64(len(fetcher.seenRead))) p.accountLoadReadMeter.Mark(int64(len(fetcher.seenReadAddr)))
p.accountLoadWriteMeter.Mark(int64(len(fetcher.seenWrite))) p.accountLoadWriteMeter.Mark(int64(len(fetcher.seenWriteAddr)))
p.accountDupReadMeter.Mark(int64(fetcher.dupsRead)) p.accountDupReadMeter.Mark(int64(fetcher.dupsRead))
p.accountDupWriteMeter.Mark(int64(fetcher.dupsWrite)) p.accountDupWriteMeter.Mark(int64(fetcher.dupsWrite))
p.accountDupCrossMeter.Mark(int64(fetcher.dupsCross)) p.accountDupCrossMeter.Mark(int64(fetcher.dupsCross))
for _, key := range fetcher.used { for _, key := range fetcher.usedAddr {
delete(fetcher.seenRead, string(key)) delete(fetcher.seenReadAddr, key)
delete(fetcher.seenWrite, string(key)) delete(fetcher.seenWriteAddr, key)
} }
p.accountWasteMeter.Mark(int64(len(fetcher.seenRead) + len(fetcher.seenWrite))) p.accountWasteMeter.Mark(int64(len(fetcher.seenReadAddr) + len(fetcher.seenWriteAddr)))
} else { } else {
p.storageLoadReadMeter.Mark(int64(len(fetcher.seenRead))) p.storageLoadReadMeter.Mark(int64(len(fetcher.seenReadSlot)))
p.storageLoadWriteMeter.Mark(int64(len(fetcher.seenWrite))) p.storageLoadWriteMeter.Mark(int64(len(fetcher.seenWriteSlot)))
p.storageDupReadMeter.Mark(int64(fetcher.dupsRead)) p.storageDupReadMeter.Mark(int64(fetcher.dupsRead))
p.storageDupWriteMeter.Mark(int64(fetcher.dupsWrite)) p.storageDupWriteMeter.Mark(int64(fetcher.dupsWrite))
p.storageDupCrossMeter.Mark(int64(fetcher.dupsCross)) p.storageDupCrossMeter.Mark(int64(fetcher.dupsCross))
for _, key := range fetcher.used { for _, key := range fetcher.usedSlot {
delete(fetcher.seenRead, string(key)) delete(fetcher.seenReadSlot, key)
delete(fetcher.seenWrite, string(key)) delete(fetcher.seenWriteSlot, key)
} }
p.storageWasteMeter.Mark(int64(len(fetcher.seenRead) + len(fetcher.seenWrite))) p.storageWasteMeter.Mark(int64(len(fetcher.seenReadSlot) + len(fetcher.seenWriteSlot)))
} }
} }
} }
@ -158,7 +158,7 @@ func (p *triePrefetcher) report() {
// upon the same contract, the parameters invoking this method may be // upon the same contract, the parameters invoking this method may be
// repeated. // repeated.
// 2. Finalize of the main account trie. This happens only once per block. // 2. Finalize of the main account trie. This happens only once per block.
func (p *triePrefetcher) prefetch(owner common.Hash, root common.Hash, addr common.Address, keys [][]byte, read bool) error { func (p *triePrefetcher) prefetch(owner common.Hash, root common.Hash, addr common.Address, addrs []common.Address, slots []common.Hash, read bool) error {
// If the state item is only being read, but reads are disabled, return // If the state item is only being read, but reads are disabled, return
if read && p.noreads { if read && p.noreads {
return nil return nil
@ -175,7 +175,7 @@ func (p *triePrefetcher) prefetch(owner common.Hash, root common.Hash, addr comm
fetcher = newSubfetcher(p.db, p.root, owner, root, addr) fetcher = newSubfetcher(p.db, p.root, owner, root, addr)
p.fetchers[id] = fetcher p.fetchers[id] = fetcher
} }
return fetcher.schedule(keys, read) return fetcher.schedule(addrs, slots, read)
} }
// trie returns the trie matching the root hash, blocking until the fetcher of // trie returns the trie matching the root hash, blocking until the fetcher of
@ -195,10 +195,12 @@ func (p *triePrefetcher) trie(owner common.Hash, root common.Hash) Trie {
// used marks a batch of state items used to allow creating statistics as to // used marks a batch of state items used to allow creating statistics as to
// how useful or wasteful the fetcher is. // how useful or wasteful the fetcher is.
func (p *triePrefetcher) used(owner common.Hash, root common.Hash, used [][]byte) { func (p *triePrefetcher) used(owner common.Hash, root common.Hash, usedAddr []common.Address, usedSlot []common.Hash) {
if fetcher := p.fetchers[p.trieID(owner, root)]; fetcher != nil { if fetcher := p.fetchers[p.trieID(owner, root)]; fetcher != nil {
fetcher.wait() // ensure the fetcher's idle before poking in its internals fetcher.wait() // ensure the fetcher's idle before poking in its internals
fetcher.used = append(fetcher.used, used...)
fetcher.usedAddr = append(fetcher.usedAddr, usedAddr...)
fetcher.usedSlot = append(fetcher.usedSlot, usedSlot...)
} }
} }
@ -235,44 +237,50 @@ type subfetcher struct {
stop chan struct{} // Channel to interrupt processing stop chan struct{} // Channel to interrupt processing
term chan struct{} // Channel to signal interruption term chan struct{} // Channel to signal interruption
seenRead map[string]struct{} // Tracks the entries already loaded via read operations seenReadAddr map[common.Address]struct{} // Tracks the accounts already loaded via read operations
seenWrite map[string]struct{} // Tracks the entries already loaded via write operations seenWriteAddr map[common.Address]struct{} // Tracks the accounts already loaded via write operations
seenReadSlot map[common.Hash]struct{} // Tracks the storage already loaded via read operations
seenWriteSlot map[common.Hash]struct{} // Tracks the storage already loaded via write operations
dupsRead int // Number of duplicate preload tasks via reads only dupsRead int // Number of duplicate preload tasks via reads only
dupsWrite int // Number of duplicate preload tasks via writes only dupsWrite int // Number of duplicate preload tasks via writes only
dupsCross int // Number of duplicate preload tasks via read-write-crosses dupsCross int // Number of duplicate preload tasks via read-write-crosses
used [][]byte // Tracks the entries used in the end usedAddr []common.Address // Tracks the accounts used in the end
usedSlot []common.Hash // Tracks the storage used in the end
} }
// subfetcherTask is a trie path to prefetch, tagged with whether it originates // subfetcherTask is a trie path to prefetch, tagged with whether it originates
// from a read or a write request. // from a read or a write request.
type subfetcherTask struct { type subfetcherTask struct {
read bool read bool
key []byte addr *common.Address
slot *common.Hash
} }
// newSubfetcher creates a goroutine to prefetch state items belonging to a // newSubfetcher creates a goroutine to prefetch state items belonging to a
// particular root hash. // particular root hash.
func newSubfetcher(db Database, state common.Hash, owner common.Hash, root common.Hash, addr common.Address) *subfetcher { func newSubfetcher(db Database, state common.Hash, owner common.Hash, root common.Hash, addr common.Address) *subfetcher {
sf := &subfetcher{ sf := &subfetcher{
db: db, db: db,
state: state, state: state,
owner: owner, owner: owner,
root: root, root: root,
addr: addr, addr: addr,
wake: make(chan struct{}, 1), wake: make(chan struct{}, 1),
stop: make(chan struct{}), stop: make(chan struct{}),
term: make(chan struct{}), term: make(chan struct{}),
seenRead: make(map[string]struct{}), seenReadAddr: make(map[common.Address]struct{}),
seenWrite: make(map[string]struct{}), seenWriteAddr: make(map[common.Address]struct{}),
seenReadSlot: make(map[common.Hash]struct{}),
seenWriteSlot: make(map[common.Hash]struct{}),
} }
go sf.loop() go sf.loop()
return sf return sf
} }
// schedule adds a batch of trie keys to the queue to prefetch. // schedule adds a batch of trie keys to the queue to prefetch.
func (sf *subfetcher) schedule(keys [][]byte, read bool) error { func (sf *subfetcher) schedule(addrs []common.Address, slots []common.Hash, read bool) error {
// Ensure the subfetcher is still alive // Ensure the subfetcher is still alive
select { select {
case <-sf.term: case <-sf.term:
@ -281,8 +289,11 @@ func (sf *subfetcher) schedule(keys [][]byte, read bool) error {
} }
// Append the tasks to the current queue // Append the tasks to the current queue
sf.lock.Lock() sf.lock.Lock()
for _, key := range keys { for _, addr := range addrs {
sf.tasks = append(sf.tasks, &subfetcherTask{read: read, key: key}) sf.tasks = append(sf.tasks, &subfetcherTask{read: read, addr: &addr})
}
for _, slot := range slots {
sf.tasks = append(sf.tasks, &subfetcherTask{read: read, slot: &slot})
} }
sf.lock.Unlock() sf.lock.Unlock()
@ -378,35 +389,66 @@ func (sf *subfetcher) loop() {
sf.lock.Unlock() sf.lock.Unlock()
for _, task := range tasks { for _, task := range tasks {
key := string(task.key) if task.addr != nil {
if task.read { key := *task.addr
if _, ok := sf.seenRead[key]; ok { if task.read {
sf.dupsRead++ if _, ok := sf.seenReadAddr[key]; ok {
continue sf.dupsRead++
} continue
if _, ok := sf.seenWrite[key]; ok { }
sf.dupsCross++ if _, ok := sf.seenWriteAddr[key]; ok {
continue sf.dupsCross++
continue
}
} else {
if _, ok := sf.seenReadAddr[key]; ok {
sf.dupsCross++
continue
}
if _, ok := sf.seenWriteAddr[key]; ok {
sf.dupsWrite++
continue
}
} }
} else { } else {
if _, ok := sf.seenRead[key]; ok { key := *task.slot
sf.dupsCross++ if task.read {
continue if _, ok := sf.seenReadSlot[key]; ok {
} sf.dupsRead++
if _, ok := sf.seenWrite[key]; ok { continue
sf.dupsWrite++ }
continue if _, ok := sf.seenWriteSlot[key]; ok {
sf.dupsCross++
continue
}
} else {
if _, ok := sf.seenReadSlot[key]; ok {
sf.dupsCross++
continue
}
if _, ok := sf.seenWriteSlot[key]; ok {
sf.dupsWrite++
continue
}
} }
} }
if len(task.key) == common.AddressLength { if task.addr != nil {
sf.trie.GetAccount(common.BytesToAddress(task.key)) sf.trie.GetAccount(*task.addr)
} else { } else {
sf.trie.GetStorage(sf.addr, task.key) sf.trie.GetStorage(sf.addr, (*task.slot)[:])
} }
if task.read { if task.read {
sf.seenRead[key] = struct{}{} if task.addr != nil {
sf.seenReadAddr[*task.addr] = struct{}{}
} else {
sf.seenReadSlot[*task.slot] = struct{}{}
}
} else { } else {
sf.seenWrite[key] = struct{}{} if task.addr != nil {
sf.seenWriteAddr[*task.addr] = struct{}{}
} else {
sf.seenWriteSlot[*task.slot] = struct{}{}
}
} }
} }

@ -53,12 +53,12 @@ func TestUseAfterTerminate(t *testing.T) {
prefetcher := newTriePrefetcher(db.db, db.originalRoot, "", true) prefetcher := newTriePrefetcher(db.db, db.originalRoot, "", true)
skey := common.HexToHash("aaa") skey := common.HexToHash("aaa")
if err := prefetcher.prefetch(common.Hash{}, db.originalRoot, common.Address{}, [][]byte{skey.Bytes()}, false); err != nil { if err := prefetcher.prefetch(common.Hash{}, db.originalRoot, common.Address{}, nil, []common.Hash{skey}, false); err != nil {
t.Errorf("Prefetch failed before terminate: %v", err) t.Errorf("Prefetch failed before terminate: %v", err)
} }
prefetcher.terminate(false) prefetcher.terminate(false)
if err := prefetcher.prefetch(common.Hash{}, db.originalRoot, common.Address{}, [][]byte{skey.Bytes()}, false); err == nil { if err := prefetcher.prefetch(common.Hash{}, db.originalRoot, common.Address{}, nil, []common.Hash{skey}, false); err == nil {
t.Errorf("Prefetch succeeded after terminate: %v", err) t.Errorf("Prefetch succeeded after terminate: %v", err)
} }
if tr := prefetcher.trie(common.Hash{}, db.originalRoot); tr == nil { if tr := prefetcher.trie(common.Hash{}, db.originalRoot); tr == nil {
@ -90,14 +90,10 @@ func TestVerklePrefetcher(t *testing.T) {
fetcher := newTriePrefetcher(sdb, root, "", false) fetcher := newTriePrefetcher(sdb, root, "", false)
// Read account // Read account
fetcher.prefetch(common.Hash{}, root, common.Address{}, [][]byte{ fetcher.prefetch(common.Hash{}, root, common.Address{}, []common.Address{addr}, nil, false)
addr.Bytes(),
}, false)
// Read storage slot // Read storage slot
fetcher.prefetch(crypto.Keccak256Hash(addr.Bytes()), sRoot, addr, [][]byte{ fetcher.prefetch(crypto.Keccak256Hash(addr.Bytes()), sRoot, addr, nil, []common.Hash{skey}, false)
skey.Bytes(),
}, false)
fetcher.terminate(false) fetcher.terminate(false)
accountTrie := fetcher.trie(common.Hash{}, root) accountTrie := fetcher.trie(common.Hash{}, root)