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native/std: restrict amount of items in JSON deserialization

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Signed-off-by: Evgeniy Stratonikov <evgeniy@nspcc.ru>
This commit is contained in:
Evgeniy Stratonikov 2021-08-02 13:28:12 +03:00
parent 06c3dda5d1
commit bdb9748c1b
3 changed files with 38 additions and 5 deletions
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2
pkg/core/native/std.go
View file

@ -204,7 +204,7 @@ func (s *Std) jsonDeserialize(_ *interop.Context, args []stackitem.Item) stackit
panic(err)
}
item, err := stackitem.FromJSON(data)
item, err := stackitem.FromJSON(data, stackitem.MaxDeserialized)
if err != nil {
panic(err)
}

20
pkg/vm/stackitem/json.go
View file

@ -15,6 +15,7 @@ import (
type decoder struct {
json.Decoder
count int
depth int
}
@ -157,8 +158,11 @@ func itemToJSONString(it Item) ([]byte, error) {
// null -> Null
// array -> Array
// map -> Map, keys are UTF-8
func FromJSON(data []byte) (Item, error) {
d := decoder{Decoder: *json.NewDecoder(bytes.NewReader(data))}
func FromJSON(data []byte, maxCount int) (Item, error) {
d := decoder{
Decoder: *json.NewDecoder(bytes.NewReader(data)),
count: maxCount,
}
if item, err := d.decode(); err != nil {
return nil, err
} else if _, err := d.Token(); err != gio.EOF {
@ -173,6 +177,12 @@ func (d *decoder) decode() (Item, error) {
if err != nil {
return nil, err
}
d.count--
if d.count < 0 && tok != json.Delim('}') && tok != json.Delim(']') {
return nil, errTooBigElements
}
switch t := tok.(type) {
case json.Delim:
switch t {
@ -190,6 +200,7 @@ func (d *decoder) decode() (Item, error) {
d.depth--
return item, err
default:
d.count++
// no error above means corresponding closing token
// was encountered for map or array respectively
return nil, nil
@ -234,6 +245,11 @@ func (d *decoder) decodeMap() (*Map, error) {
if !ok {
return m, nil
}
d.count--
if d.count < 0 {
return nil, errTooBigElements
}
val, err := d.decode()
if err != nil {
return nil, err

21
pkg/vm/stackitem/json_test.go
View file

@ -11,7 +11,7 @@ import (
func getTestDecodeFunc(js string, expected ...interface{}) func(t *testing.T) {
return func(t *testing.T) {
actual, err := FromJSON([]byte(js))
actual, err := FromJSON([]byte(js), 20)
if expected[0] == nil {
require.Error(t, err)
return
@ -50,6 +50,14 @@ func TestFromToJSON(t *testing.T) {
NewArray([]Item{NewBigInteger(big.NewInt(1)), NewByteArray([]byte("test")), NewBool(true), Null{}})))
t.Run("Nested", getTestDecodeFunc(`[[],[{},null]]`,
NewArray([]Item{NewArray([]Item{}), NewArray([]Item{NewMap(), Null{}})})))
t.Run("ManyElements", func(t *testing.T) {
js := `[1, 2, 3]` // 3 elements + array itself
_, err := FromJSON([]byte(js), 4)
require.NoError(t, err)
_, err = FromJSON([]byte(js), 3)
require.True(t, errors.Is(err, errTooBigElements), err)
})
})
t.Run("Map", func(t *testing.T) {
small := NewMap()
@ -64,6 +72,15 @@ func TestFromToJSON(t *testing.T) {
m := NewMap()
m.Add(NewByteArray([]byte("\t")), NewBool(true))
t.Run("escape keys", getTestDecodeFunc(`{"\t":true}`, m))
t.Run("ManyElements", func(t *testing.T) {
js := `{"a":1,"b":3}` // 4 elements + map itself
_, err := FromJSON([]byte(js), 5)
require.NoError(t, err)
_, err = FromJSON([]byte(js), 4)
require.True(t, errors.Is(err, errTooBigElements), err)
})
})
t.Run("Invalid", func(t *testing.T) {
t.Run("Empty", getTestDecodeFunc(``, nil))
@ -114,7 +131,7 @@ func testToJSON(t *testing.T, expectedErr error, item Item) {
}
require.NoError(t, err)
actual, err := FromJSON(data)
actual, err := FromJSON(data, 1024)
require.NoError(t, err)
require.Equal(t, item, actual)
}