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vm: restrict SHL/SHR arguments to -256..256

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Also unify SHL/SHR implementation.
This commit is contained in:
Evgenii Stratonikov 2019-09-18 14:35:29 +03:00
parent 4a8be486f0
commit 3c53beca82
2 changed files with 32 additions and 11 deletions
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25
pkg/vm/vm.go
View file

@ -22,6 +22,11 @@ var (
ModeMute Mode = 1 << 0
)
const (
maxSHLArg = 256
minSHLArg = -256
)
// VM represents the virtual machine.
type VM struct {
state State
@ -508,21 +513,19 @@ func (v *VM) execute(ctx *Context, op Instruction) {
a := v.estack.Pop().BigInt()
v.estack.PushVal(new(big.Int).Mod(a, b))
case SHL:
b := v.estack.Pop().BigInt()
if b.Int64() == 0 {
case SHL, SHR:
b := v.estack.Pop().BigInt().Int64()
if b == 0 {
return
} else if b < minSHLArg || b > maxSHLArg {
panic(fmt.Sprintf("operand must be between %d and %d", minSHLArg, maxSHLArg))
}
a := v.estack.Pop().BigInt()
v.estack.PushVal(new(big.Int).Lsh(a, uint(b.Int64())))
case SHR:
b := v.estack.Pop().BigInt()
if b.Int64() == 0 {
return
if op == SHL {
v.estack.PushVal(new(big.Int).Lsh(a, uint(b)))
} else {
v.estack.PushVal(new(big.Int).Rsh(a, uint(b)))
}
a := v.estack.Pop().BigInt()
v.estack.PushVal(new(big.Int).Rsh(a, uint(b.Int64())))
case BOOLAND:
b := v.estack.Pop().Bool()

18
pkg/vm/vm_test.go
View file

@ -305,6 +305,15 @@ func TestSHRZero(t *testing.T) {
assert.Equal(t, makeStackItem([]byte{0, 1}), vm.estack.Pop().value)
}
func TestSHRSmallValue(t *testing.T) {
prog := makeProgram(SHR)
vm := load(prog)
vm.estack.PushVal(5)
vm.estack.PushVal(-257)
vm.Run()
assert.Equal(t, true, vm.state.HasFlag(faultState))
}
func TestSHLGood(t *testing.T) {
prog := makeProgram(SHL)
vm := load(prog)
@ -327,6 +336,15 @@ func TestSHLZero(t *testing.T) {
assert.Equal(t, makeStackItem([]byte{0, 1}), vm.estack.Pop().value)
}
func TestSHLBigValue(t *testing.T) {
prog := makeProgram(SHL)
vm := load(prog)
vm.estack.PushVal(5)
vm.estack.PushVal(257)
vm.Run()
assert.Equal(t, true, vm.state.HasFlag(faultState))
}
func TestLT(t *testing.T) {
prog := makeProgram(LT)
vm := load(prog)