trie/bintrie: fix GetAccount/GetStorage non-membership — verify stem before returning values (#34690)

Fix `GetAccount` returning **wrong account data** for non-existent
addresses when the trie root is a `StemNode` (single-account trie) — the
`StemNode` branch returned `r.Values` without verifying the queried
address's stem matches.

Co-authored-by: Guillaume Ballet <3272758+gballet@users.noreply.github.com>

trie/bintrie/stem_node.go

@@ -37,7 +37,10 @@ type StemNode struct {
 
 // Get retrieves the value for the given key.
 func (bt *StemNode) Get(key []byte, _ NodeResolverFn) ([]byte, error) {
-	panic("this should not be called directly")
+	if !bytes.Equal(bt.Stem, key[:StemSize]) {
+		return nil, nil
+	}
+	return bt.Values[key[StemSize]], nil
 }
 
 // Insert inserts a new key-value pair into the node.

trie/bintrie/stem_node_test.go

@@ -23,6 +23,50 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 )
 
+// TestStemNodeGet tests the Get method for matching stem, non-matching stem,
+// and nil-value suffix scenarios.
+func TestStemNodeGet(t *testing.T) {
+	stem := make([]byte, StemSize)
+	stem[0] = 0xAB
+	var values [StemNodeWidth][]byte
+	values[5] = common.HexToHash("0xdeadbeef").Bytes()
+
+	node := &StemNode{Stem: stem, Values: values[:], depth: 0}
+
+	// Matching stem, populated suffix → returns value.
+	key := make([]byte, HashSize)
+	copy(key[:StemSize], stem)
+	key[StemSize] = 5
+	got, err := node.Get(key, nil)
+	if err != nil {
+		t.Fatalf("Get error: %v", err)
+	}
+	if !bytes.Equal(got, values[5]) {
+		t.Fatalf("Get = %x, want %x", got, values[5])
+	}
+
+	// Matching stem, empty suffix → returns nil (slot not set).
+	key[StemSize] = 99
+	got, err = node.Get(key, nil)
+	if err != nil {
+		t.Fatalf("Get error: %v", err)
+	}
+	if got != nil {
+		t.Fatalf("Get(empty suffix) = %x, want nil", got)
+	}
+
+	// Non-matching stem → returns nil, nil.
+	otherKey := make([]byte, HashSize)
+	otherKey[0] = 0xFF
+	got, err = node.Get(otherKey, nil)
+	if err != nil {
+		t.Fatalf("Get error: %v", err)
+	}
+	if got != nil {
+		t.Fatalf("Get(wrong stem) = %x, want nil", got)
+	}
+}
+
 // TestStemNodeInsertSameStem tests inserting values with the same stem
 func TestStemNodeInsertSameStem(t *testing.T) {
 	stem := make([]byte, 31)

trie/bintrie/trie.go

@@ -191,7 +191,7 @@ func (t *BinaryTrie) GetAccount(addr common.Address) (*types.StateAccount, error
 	case *InternalNode:
 		values, err = r.GetValuesAtStem(key[:StemSize], t.nodeResolver)
 	case *StemNode:
-		values = r.Values
+		values, err = r.GetValuesAtStem(key[:StemSize], t.nodeResolver)
 	case Empty:
 		return nil, nil
 	default:

trie/bintrie/trie_test.go

@@ -620,3 +620,162 @@ func TestBinaryTrieWitness(t *testing.T) {
 		t.Fatal("unexpected witness value for path2")
 	}
 }
+
+// testAccount is a helper that creates a BinaryTrie with a tracer and
+// inserts a single account, returning the trie.
+func testAccount(t *testing.T, addr common.Address, nonce uint64, balance uint64) *BinaryTrie {
+	t.Helper()
+	tr := &BinaryTrie{
+		root:   NewBinaryNode(),
+		tracer: trie.NewPrevalueTracer(),
+	}
+	acc := &types.StateAccount{
+		Nonce:    nonce,
+		Balance:  uint256.NewInt(balance),
+		CodeHash: types.EmptyCodeHash[:],
+	}
+	if err := tr.UpdateAccount(addr, acc, 0); err != nil {
+		t.Fatalf("UpdateAccount error: %v", err)
+	}
+	return tr
+}
+
+// TestGetAccountNonMembershipStemRoot verifies that querying a non-existent
+// address returns nil when the trie root is a StemNode (single-account trie).
+// This is a regression test: previously the StemNode branch in GetAccount
+// returned the root's values without verifying the stem.
+func TestGetAccountNonMembershipStemRoot(t *testing.T) {
+	addr := common.HexToAddress("0x1111111111111111111111111111111111111111")
+	tr := testAccount(t, addr, 42, 100)
+
+	// Verify root is a StemNode (single stem inserted).
+	if _, ok := tr.root.(*StemNode); !ok {
+		t.Fatalf("expected StemNode root, got %T", tr.root)
+	}
+
+	// Query a completely different address — must return nil.
+	other := common.HexToAddress("0x2222222222222222222222222222222222222222")
+	got, err := tr.GetAccount(other)
+	if err != nil {
+		t.Fatalf("GetAccount error: %v", err)
+	}
+	if got != nil {
+		t.Fatalf("expected nil for non-existent account, got nonce=%d balance=%s", got.Nonce, got.Balance)
+	}
+
+	// Original account must still be retrievable.
+	got, err = tr.GetAccount(addr)
+	if err != nil {
+		t.Fatalf("GetAccount(original) error: %v", err)
+	}
+	if got == nil {
+		t.Fatal("expected original account, got nil")
+	}
+	if got.Nonce != 42 {
+		t.Fatalf("expected nonce=42, got %d", got.Nonce)
+	}
+}
+
+// TestGetAccountNonMembershipInternalRoot verifies that querying a non-existent
+// address returns nil when the trie root is an InternalNode (multi-account trie).
+func TestGetAccountNonMembershipInternalRoot(t *testing.T) {
+	tr := &BinaryTrie{
+		root:   NewBinaryNode(),
+		tracer: trie.NewPrevalueTracer(),
+	}
+
+	// Insert two accounts whose binary tree keys have different first bits
+	// so the root splits into an InternalNode.
+	addr1 := common.HexToAddress("0x1111111111111111111111111111111111111111")
+	addr2 := common.HexToAddress("0x9999999999999999999999999999999999999999")
+	for _, addr := range []common.Address{addr1, addr2} {
+		acc := &types.StateAccount{
+			Nonce:    1,
+			Balance:  uint256.NewInt(1),
+			CodeHash: types.EmptyCodeHash[:],
+		}
+		if err := tr.UpdateAccount(addr, acc, 0); err != nil {
+			t.Fatalf("UpdateAccount error: %v", err)
+		}
+	}
+
+	// Verify root is an InternalNode.
+	if _, ok := tr.root.(*InternalNode); !ok {
+		t.Fatalf("expected InternalNode root, got %T", tr.root)
+	}
+
+	// Query a non-existent address — must return nil.
+	other := common.HexToAddress("0x5555555555555555555555555555555555555555")
+	got, err := tr.GetAccount(other)
+	if err != nil {
+		t.Fatalf("GetAccount error: %v", err)
+	}
+	if got != nil {
+		t.Fatalf("expected nil for non-existent account, got nonce=%d", got.Nonce)
+	}
+}
+
+// TestGetStorageNonMembershipStemRoot verifies that querying storage for a
+// non-existent address returns nil when the root is a StemNode. This is a
+// regression test: previously StemNode.Get panicked unconditionally.
+func TestGetStorageNonMembershipStemRoot(t *testing.T) {
+	addr := common.HexToAddress("0x1111111111111111111111111111111111111111")
+	tr := testAccount(t, addr, 1, 100)
+
+	// Verify root is a StemNode.
+	if _, ok := tr.root.(*StemNode); !ok {
+		t.Fatalf("expected StemNode root, got %T", tr.root)
+	}
+
+	// Query storage for a different address — must return nil, not panic.
+	other := common.HexToAddress("0x2222222222222222222222222222222222222222")
+	slot := common.HexToHash("0x01")
+	got, err := tr.GetStorage(other, slot[:])
+	if err != nil {
+		t.Fatalf("GetStorage error: %v", err)
+	}
+	if len(got) > 0 && !bytes.Equal(got, zero[:]) {
+		t.Fatalf("expected nil/zero for non-existent storage, got %x", got)
+	}
+}
+
+// TestGetStorageNonMembershipInternalRoot verifies that querying storage for a
+// non-existent address returns nil when the root is an InternalNode.
+func TestGetStorageNonMembershipInternalRoot(t *testing.T) {
+	tr := &BinaryTrie{
+		root:   NewBinaryNode(),
+		tracer: trie.NewPrevalueTracer(),
+	}
+
+	addr := common.HexToAddress("0x1234567890abcdef1234567890abcdef12345678")
+	acc := &types.StateAccount{
+		Nonce:    1,
+		Balance:  uint256.NewInt(1000),
+		CodeHash: types.EmptyCodeHash[:],
+	}
+	if err := tr.UpdateAccount(addr, acc, 0); err != nil {
+		t.Fatalf("UpdateAccount error: %v", err)
+	}
+
+	// Add a storage slot so the root becomes an InternalNode (storage
+	// slots use a different stem than account data).
+	slot := common.HexToHash("0xFF")
+	val := common.TrimLeftZeroes(common.HexToHash("0xdeadbeef").Bytes())
+	if err := tr.UpdateStorage(addr, slot[:], val); err != nil {
+		t.Fatalf("UpdateStorage error: %v", err)
+	}
+
+	if _, ok := tr.root.(*InternalNode); !ok {
+		t.Fatalf("expected InternalNode root, got %T", tr.root)
+	}
+
+	// Query storage for a non-existent address — must return nil.
+	other := common.HexToAddress("0x9999999999999999999999999999999999999999")
+	got, err := tr.GetStorage(other, slot[:])
+	if err != nil {
+		t.Fatalf("GetStorage error: %v", err)
+	}
+	if len(got) > 0 && !bytes.Equal(got, zero[:]) {
+		t.Fatalf("expected nil/zero for non-existent storage, got %x", got)
+	}
+}