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Merge pull request #1433 from nspcc-dev/vm/maxcomparablesize

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vm: add MaxComparableSize and check reference counter after PACK-UNPACK
This commit is contained in:
Roman Khimov 2020-09-29 18:57:45 +03:00 committed by GitHub
commit 230352d99f
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GPG key ID: 4AEE18F83AFDEB23
7 changed files with 119 additions and 26 deletions
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1
docs/compiler.md
View file

@ -24,6 +24,7 @@ a dialect of Go rather than a complete port of the language:
overhead for all contracts. This can easily be mitigated by first storing values
in variables and returning the result.
* lambdas are supported, but closures are not.
* maps are supported, but valid map keys are booleans, integers and strings with length <= 64
## VM API (interop layer)
Compiler translates interop function calls into NEO VM syscalls or (for custom

50
pkg/vm/stackitem/item.go
View file

@ -7,6 +7,7 @@ import (
"encoding/json"
"errors"
"fmt"
"math"
"math/big"
"reflect"
"unicode/utf8"
@ -16,14 +17,19 @@ import (
"github.com/nspcc-dev/neo-go/pkg/util"
)
const (
// MaxBigIntegerSizeBits is the maximum size of BigInt item in bits.
const MaxBigIntegerSizeBits = 32 * 8
MaxBigIntegerSizeBits = 32 * 8
// MaxArraySize is the maximum array size allowed in the VM.
const MaxArraySize = 1024
MaxArraySize = 1024
// MaxSize is the maximum item size allowed in the VM.
const MaxSize = 1024 * 1024
MaxSize = 1024 * 1024
// MaxByteArrayComparableSize is the maximum allowed length of ByteArray for Equals method.
// It is set to be the maximum uint16 value.
MaxByteArrayComparableSize = math.MaxUint16
// MaxKeySize is the maximum size of map key.
MaxKeySize = 64
)
// Item represents the "real" value that is pushed on the stack.
type Item interface {
@ -46,7 +52,10 @@ type Item interface {
Convert(Type) (Item, error)
}
var errInvalidConversion = errors.New("invalid conversion type")
var (
errInvalidConversion = errors.New("invalid conversion type")
errExceedingMaxComparableSize = errors.New("the operand exceeds the maximum comparable size")
)
// Make tries to make appropriate stack item from provided value.
// It will panic if it's not possible.
@ -536,13 +545,22 @@ func (i *ByteArray) TryInteger() (*big.Int, error) {
// Equals implements Item interface.
func (i *ByteArray) Equals(s Item) bool {
if len(i.value) > MaxByteArrayComparableSize {
panic(errExceedingMaxComparableSize)
}
if i == s {
return true
} else if s == nil {
return false
}
val, ok := s.(*ByteArray)
return ok && bytes.Equal(i.value, val.value)
if !ok {
return false
}
if len(val.value) > MaxByteArrayComparableSize {
panic(errExceedingMaxComparableSize)
}
return bytes.Equal(i.value, val.value)
}
// Dup implements Item interface.
@ -757,8 +775,8 @@ func (i *Map) Convert(typ Type) (Item, error) {
// Add adds key-value pair to the map.
func (i *Map) Add(key, value Item) {
if !IsValidMapKey(key) {
panic("wrong key type")
if err := IsValidMapKey(key); err != nil {
panic(err)
}
index := i.Index(key)
if index >= 0 {
@ -776,12 +794,18 @@ func (i *Map) Drop(index int) {
// IsValidMapKey checks whether it's possible to use given Item as a Map
// key.
func IsValidMapKey(key Item) bool {
func IsValidMapKey(key Item) error {
switch key.(type) {
case *Bool, *BigInteger, *ByteArray:
return true
case *Bool, *BigInteger:
return nil
case *ByteArray:
size := len(key.Value().([]byte))
if size > MaxKeySize {
return fmt.Errorf("invalid map key size: %d", size)
}
return nil
default:
return false
return fmt.Errorf("invalid map key of type %s", key.Type())
}
}

22
pkg/vm/stackitem/item_test.go
View file

@ -143,6 +143,7 @@ var equalsTestCases = map[string][]struct {
item1 Item
item2 Item
result bool
panics bool
}{
"struct": {
{
@ -251,6 +252,21 @@ var equalsTestCases = map[string][]struct {
item2: Make([]byte{1, 2, 3}),
result: true,
},
{
item1: NewByteArray(make([]byte, MaxByteArrayComparableSize+1)),
item2: NewByteArray([]byte{1, 2, 3}),
panics: true,
},
{
item1: NewByteArray([]byte{1, 2, 3}),
item2: NewByteArray(make([]byte, MaxByteArrayComparableSize+1)),
panics: true,
},
{
item1: NewByteArray(make([]byte, MaxByteArrayComparableSize+1)),
item2: NewByteArray(make([]byte, MaxByteArrayComparableSize+1)),
panics: true,
},
},
"array": {
{
@ -350,9 +366,15 @@ func TestEquals(t *testing.T) {
for name, testBatch := range equalsTestCases {
for _, testCase := range testBatch {
t.Run(name, func(t *testing.T) {
if testCase.panics {
assert.Panics(t, func() {
testCase.item1.Equals(testCase.item2)
})
} else {
assert.Equal(t, testCase.result, testCase.item1.Equals(testCase.item2))
// Reference equals
assert.Equal(t, true, testCase.item1.Equals(testCase.item1))
}
})
}
}

4
pkg/vm/stackitem/json.go
View file

@ -360,8 +360,8 @@ func FromJSONWithTypes(data []byte) (Item, error) {
key, err := FromJSONWithTypes(arr[i].Key)
if err != nil {
return nil, err
} else if !IsValidMapKey(key) {
return nil, fmt.Errorf("invalid map key of type %s", key.Type())
} else if err = IsValidMapKey(key); err != nil {
return nil, err
}
value, err := FromJSONWithTypes(arr[i].Value)
if err != nil {

2
pkg/vm/stackitem/json_test.go
View file

@ -88,7 +88,7 @@ func TestFromToJSON(t *testing.T) {
t.Run("BigNestedArray", getTestDecodeFunc(`[[[[[[[[[[[]]]]]]]]]]]`, nil))
t.Run("EncodeRecursive", func(t *testing.T) {
// add this item to speed up test a bit
item := NewByteArray(make([]byte, MaxSize/100))
item := NewByteArray(make([]byte, MaxKeySize))
t.Run("Array", func(t *testing.T) {
arr := NewArray([]Item{item})
arr.Append(arr)

8
pkg/vm/vm.go
View file

@ -531,8 +531,8 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
v.estack.PushVal(stackitem.Null{})
case opcode.ISNULL:
res := v.estack.Pop().value.Equals(stackitem.Null{})
v.estack.PushVal(res)
_, ok := v.estack.Pop().value.(stackitem.Null)
v.estack.PushVal(ok)
case opcode.ISTYPE:
res := v.estack.Pop().Item()
@ -1668,8 +1668,8 @@ func validateMapKey(key *Element) {
if key == nil {
panic("no key found")
}
if !stackitem.IsValidMapKey(key.Item()) {
panic("key can't be a collection")
if err := stackitem.IsValidMapKey(key.Item()); err != nil {
panic(err)
}
}

46
pkg/vm/vm_test.go
View file

@ -2031,6 +2031,52 @@ func TestPACKGood(t *testing.T) {
assert.Equal(t, int64(1), vm.estack.Peek(1).BigInt().Int64())
}
func TestPACK_UNPACK_MaxSize(t *testing.T) {
prog := makeProgram(opcode.PACK, opcode.UNPACK)
elements := make([]int, stackitem.MaxArraySize)
vm := load(prog)
// canary
vm.estack.PushVal(1)
for i := len(elements) - 1; i >= 0; i-- {
vm.estack.PushVal(elements[i])
}
vm.estack.PushVal(len(elements))
runVM(t, vm)
// check reference counter = 1+1+1024
assert.Equal(t, 1+1+len(elements), vm.refs.size)
assert.Equal(t, 1+1+len(elements), vm.estack.Len()) // canary + length + elements
assert.Equal(t, int64(len(elements)), vm.estack.Peek(0).Value().(*big.Int).Int64())
for i := 0; i < len(elements); i++ {
e, ok := vm.estack.Peek(i + 1).Value().(*big.Int)
assert.True(t, ok)
assert.Equal(t, int64(elements[i]), e.Int64())
}
assert.Equal(t, int64(1), vm.estack.Peek(1+len(elements)).BigInt().Int64())
}
func TestPACK_UNPACK_PACK_MaxSize(t *testing.T) {
prog := makeProgram(opcode.PACK, opcode.UNPACK, opcode.PACK)
elements := make([]int, stackitem.MaxArraySize)
vm := load(prog)
// canary
vm.estack.PushVal(1)
for i := len(elements) - 1; i >= 0; i-- {
vm.estack.PushVal(elements[i])
}
vm.estack.PushVal(len(elements))
runVM(t, vm)
// check reference counter = 1+1+1024
assert.Equal(t, 1+1+len(elements), vm.refs.size)
assert.Equal(t, 2, vm.estack.Len())
a := vm.estack.Peek(0).Array()
assert.Equal(t, len(elements), len(a))
for i := 0; i < len(elements); i++ {
e := a[i].Value().(*big.Int)
assert.Equal(t, int64(elements[i]), e.Int64())
}
assert.Equal(t, int64(1), vm.estack.Peek(1).BigInt().Int64())
}
func TestUNPACKBadNotArray(t *testing.T) {
prog := makeProgram(opcode.UNPACK)
runWithArgs(t, prog, nil, 1)