vm: check Integer size on creation

pkg/vm/stack_item.go

@@ -85,9 +85,7 @@ func makeStackItem(v interface{}) StackItem {
 			value: val,
 		}
 	case *big.Int:
-		return &BigIntegerItem{
+		return NewBigIntegerItem(val)
-			value: val,
-		}
 	case StackItem:
 		return val
 	case []int:
@@ -311,6 +309,9 @@ type BigIntegerItem struct {
 
 // NewBigIntegerItem returns an new BigIntegerItem object.
 func NewBigIntegerItem(value *big.Int) *BigIntegerItem {
+	if value.BitLen() > MaxBigIntegerSizeBits {
+		panic("integer is too big")
+	}
 	return &BigIntegerItem{
 		value: value,
 	}
@@ -519,7 +520,11 @@ func (i *ByteArrayItem) TryBytes() ([]byte, error) {
 
 // TryInteger implements StackItem interface.
 func (i *ByteArrayItem) TryInteger() (*big.Int, error) {
-	return emit.BytesToInt(i.value), nil
+	bi := emit.BytesToInt(i.value)
+	if bi.BitLen() > MaxBigIntegerSizeBits {
+		return nil, errors.New("integer is too big")
+	}
+	return bi, nil
 }
 
 // Equals implements StackItem interface.

pkg/vm/vm.go

@@ -775,58 +775,43 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 	case opcode.INC:
 		x := v.estack.Pop().BigInt()
 		a := new(big.Int).Add(x, big.NewInt(1))
-		v.checkBigIntSize(a)
 		v.estack.PushVal(a)
 
 	case opcode.DEC:
 		x := v.estack.Pop().BigInt()
 		a := new(big.Int).Sub(x, big.NewInt(1))
-		v.checkBigIntSize(a)
 		v.estack.PushVal(a)
 
 	case opcode.ADD:
 		a := v.estack.Pop().BigInt()
-		v.checkBigIntSize(a)
 		b := v.estack.Pop().BigInt()
-		v.checkBigIntSize(b)
 
 		c := new(big.Int).Add(a, b)
-		v.checkBigIntSize(c)
 		v.estack.PushVal(c)
 
 	case opcode.SUB:
 		b := v.estack.Pop().BigInt()
-		v.checkBigIntSize(b)
 		a := v.estack.Pop().BigInt()
-		v.checkBigIntSize(a)
 
 		c := new(big.Int).Sub(a, b)
-		v.checkBigIntSize(c)
 		v.estack.PushVal(c)
 
 	case opcode.MUL:
 		a := v.estack.Pop().BigInt()
-		v.checkBigIntSize(a)
 		b := v.estack.Pop().BigInt()
-		v.checkBigIntSize(b)
 
 		c := new(big.Int).Mul(a, b)
-		v.checkBigIntSize(c)
 		v.estack.PushVal(c)
 
 	case opcode.DIV:
 		b := v.estack.Pop().BigInt()
-		v.checkBigIntSize(b)
 		a := v.estack.Pop().BigInt()
-		v.checkBigIntSize(a)
 
 		v.estack.PushVal(new(big.Int).Quo(a, b))
 
 	case opcode.MOD:
 		b := v.estack.Pop().BigInt()
-		v.checkBigIntSize(b)
 		a := v.estack.Pop().BigInt()
-		v.checkBigIntSize(a)
 
 		v.estack.PushVal(new(big.Int).Rem(a, b))
 
@@ -838,7 +823,6 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 			panic(fmt.Sprintf("operand must be between %d and %d", 0, maxSHLArg))
 		}
 		a := v.estack.Pop().BigInt()
-		v.checkBigIntSize(a)
 
 		var item big.Int
 		if op == opcode.SHL {
@@ -847,7 +831,6 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 			item.Rsh(a, uint(b))
 		}
 
-		v.checkBigIntSize(&item)
 		v.estack.PushVal(&item)
 
 	case opcode.NOT:
@@ -1527,12 +1510,6 @@ func (v *VM) checkInvocationStackSize() {
 	}
 }
 
-func (v *VM) checkBigIntSize(a *big.Int) {
-	if a.BitLen() > MaxBigIntegerSizeBits {
-		panic("big integer is too big")
-	}
-}
-
 // bytesToPublicKey is a helper deserializing keys using cache and panicing on
 // error.
 func (v *VM) bytesToPublicKey(b []byte) *keys.PublicKey {

pkg/vm/vm_test.go

@@ -1067,31 +1067,6 @@ func TestADDBigResult(t *testing.T) {
 	checkVMFailed(t, vm)
 }
 
-func testBigArgument(t *testing.T, inst opcode.Opcode) {
-	prog := makeProgram(inst)
-	x := getBigInt(MaxBigIntegerSizeBits, 0)
-	t.Run(inst.String()+" big 1-st argument", func(t *testing.T) {
-		vm := load(prog)
-		vm.estack.PushVal(x)
-		vm.estack.PushVal(0)
-		checkVMFailed(t, vm)
-	})
-	t.Run(inst.String()+" big 2-nd argument", func(t *testing.T) {
-		vm := load(prog)
-		vm.estack.PushVal(0)
-		vm.estack.PushVal(x)
-		checkVMFailed(t, vm)
-	})
-}
-
-func TestArithBigArgument(t *testing.T) {
-	testBigArgument(t, opcode.ADD)
-	testBigArgument(t, opcode.SUB)
-	testBigArgument(t, opcode.MUL)
-	testBigArgument(t, opcode.DIV)
-	testBigArgument(t, opcode.MOD)
-}
-
 func TestMul(t *testing.T) {
 	prog := makeProgram(opcode.MUL)
 	vm := load(prog)
@@ -1190,14 +1165,6 @@ func TestSHRNegative(t *testing.T) {
 	checkVMFailed(t, vm)
 }
 
-func TestSHRBigArgument(t *testing.T) {
-	prog := makeProgram(opcode.SHR)
-	vm := load(prog)
-	vm.estack.PushVal(getBigInt(MaxBigIntegerSizeBits, 0))
-	vm.estack.PushVal(1)
-	checkVMFailed(t, vm)
-}
-
 func TestSHLGood(t *testing.T) {
 	prog := makeProgram(opcode.SHL)
 	vm := load(prog)
@@ -1234,14 +1201,6 @@ func TestSHLBigResult(t *testing.T) {
 	checkVMFailed(t, vm)
 }
 
-func TestSHLBigArgument(t *testing.T) {
-	prog := makeProgram(opcode.SHR)
-	vm := load(prog)
-	vm.estack.PushVal(getBigInt(MaxBigIntegerSizeBits, 0))
-	vm.estack.PushVal(1)
-	checkVMFailed(t, vm)
-}
-
 func TestLT(t *testing.T) {
 	prog := makeProgram(opcode.LT)
 	vm := load(prog)