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rlp: reject non-minimal input strings

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Input strings of length 1 containing a byte < 56 are non-minimal and
should be encoded as a single byte instead. Reject such strings.
release/1.0.1
Felix Lange 10 years ago
parent 6e9f8035a1
commit 1e2c93aa2d
2 changed files with 45 additions and 15 deletions
Show all changes Ignore whitespace when comparing lines Ignore changes in amount of whitespace Ignore changes in whitespace at EOL
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  1. 28
      rlp/decode.go
  2. 32
      rlp/decode_test.go

28
rlp/decode.go
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@ -305,10 +305,11 @@ func decodeByteSlice(s *Stream, val reflect.Value) error {
return decodeListSlice(s, val, decodeUint)
}
b, err := s.Bytes()
if err == nil {
val.SetBytes(b)
if err != nil {
return wrapStreamError(err, val.Type())
}
return err
val.SetBytes(b)
return nil
}
func decodeByteArray(s *Stream, val reflect.Value) error {
@ -333,6 +334,10 @@ func decodeByteArray(s *Stream, val reflect.Value) error {
return err
}
zero(val, int(size))
// Reject cases where single byte encoding should have been used.
if size == 1 && slice[0] < 56 {
return wrapStreamError(ErrCanonSize, val.Type())
}
case List:
return decodeListArray(s, val, decodeUint)
}
@ -477,7 +482,7 @@ var (
// Actual Errors
ErrExpectedString = errors.New("rlp: expected String or Byte")
ErrExpectedList = errors.New("rlp: expected List")
ErrCanonInt = errors.New("rlp: non-canonical (leading zero bytes) integer")
ErrCanonInt = errors.New("rlp: non-canonical integer format")
ErrCanonSize = errors.New("rlp: non-canonical size information")
ErrElemTooLarge = errors.New("rlp: element is larger than containing list")
ErrValueTooLarge = errors.New("rlp: value size exceeds available input length")
@ -576,6 +581,9 @@ func (s *Stream) Bytes() ([]byte, error) {
if err = s.readFull(b); err != nil {
return nil, err
}
if size == 1 && b[0] < 56 {
return nil, ErrCanonSize
}
return b, nil
default:
return nil, ErrExpectedString
@ -631,11 +639,17 @@ func (s *Stream) uint(maxbits int) (uint64, error) {
return 0, errUintOverflow
}
v, err := s.readUint(byte(size))
if err == ErrCanonSize {
switch {
case err == ErrCanonSize:
// Adjust error because we're not reading a size right now.
err = ErrCanonInt
return 0, ErrCanonInt
case err != nil:
return 0, err
case size > 0 && v < 56:
return 0, ErrCanonSize
default:
return v, nil
}
return v, err
default:
return 0, ErrExpectedString
}

32
rlp/decode_test.go
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@ -93,12 +93,16 @@ func TestStreamErrors(t *testing.T) {
{"00", calls{"ListEnd"}, nil, errNotInList},
{"C401020304", calls{"List", "Uint", "ListEnd"}, nil, errNotAtEOL},
// Leading zero bytes are rejected when reading integers.
// Non-canonical integers (e.g. leading zero bytes).
{"00", calls{"Uint"}, nil, ErrCanonInt},
{"820002", calls{"Uint"}, nil, ErrCanonInt},
{"8133", calls{"Uint"}, nil, ErrCanonSize},
{"8156", calls{"Uint"}, nil, nil},
// Size tags must use the smallest possible encoding.
// Leading zero bytes in the size tag are also rejected.
{"8100", calls{"Uint"}, nil, ErrCanonSize},
{"8100", calls{"Bytes"}, nil, ErrCanonSize},
{"B800", calls{"Kind"}, withoutInputLimit, ErrCanonSize},
{"B90000", calls{"Kind"}, withoutInputLimit, ErrCanonSize},
{"B90055", calls{"Kind"}, withoutInputLimit, ErrCanonSize},
@ -112,7 +116,7 @@ func TestStreamErrors(t *testing.T) {
{"", calls{"Kind"}, nil, io.EOF},
{"", calls{"Uint"}, nil, io.EOF},
{"", calls{"List"}, nil, io.EOF},
{"8105", calls{"Uint", "Uint"}, nil, io.EOF},
{"8158", calls{"Uint", "Uint"}, nil, io.EOF},
{"C0", calls{"List", "ListEnd", "List"}, nil, io.EOF},
// Input limit errors.
@ -129,11 +133,11 @@ func TestStreamErrors(t *testing.T) {
// down toward zero in Stream.remaining, reading too far can overflow
// remaining to a large value, effectively disabling the limit.
{"C40102030401", calls{"Raw", "Uint"}, withCustomInputLimit(5), io.EOF},
{"C4010203048102", calls{"Raw", "Uint"}, withCustomInputLimit(6), ErrValueTooLarge},
{"C4010203048158", calls{"Raw", "Uint"}, withCustomInputLimit(6), ErrValueTooLarge},
// Check that the same calls are fine without a limit.
{"C40102030401", calls{"Raw", "Uint"}, withoutInputLimit, nil},
{"C4010203048102", calls{"Raw", "Uint"}, withoutInputLimit, nil},
{"C4010203048158", calls{"Raw", "Uint"}, withoutInputLimit, nil},
// Unexpected EOF. This only happens when there is
// no input limit, so the reader needs to be 'dumbed down'.
@ -295,13 +299,13 @@ var decodeTests = []decodeTest{
// integers
{input: "05", ptr: new(uint32), value: uint32(5)},
{input: "80", ptr: new(uint32), value: uint32(0)},
{input: "8105", ptr: new(uint32), value: uint32(5)},
{input: "820505", ptr: new(uint32), value: uint32(0x0505)},
{input: "83050505", ptr: new(uint32), value: uint32(0x050505)},
{input: "8405050505", ptr: new(uint32), value: uint32(0x05050505)},
{input: "850505050505", ptr: new(uint32), error: "rlp: input string too long for uint32"},
{input: "C0", ptr: new(uint32), error: "rlp: expected input string or byte for uint32"},
{input: "00", ptr: new(uint32), error: "rlp: non-canonical integer (leading zero bytes) for uint32"},
{input: "8105", ptr: new(uint32), error: "rlp: non-canonical size information for uint32"},
{input: "820004", ptr: new(uint32), error: "rlp: non-canonical integer (leading zero bytes) for uint32"},
{input: "B8020004", ptr: new(uint32), error: "rlp: non-canonical size information for uint32"},
@ -319,10 +323,16 @@ var decodeTests = []decodeTest{
// byte slices
{input: "01", ptr: new([]byte), value: []byte{1}},
{input: "80", ptr: new([]byte), value: []byte{}},
{input: "8D6162636465666768696A6B6C6D", ptr: new([]byte), value: []byte("abcdefghijklm")},
{input: "C0", ptr: new([]byte), value: []byte{}},
{input: "C3010203", ptr: new([]byte), value: []byte{1, 2, 3}},
{
input: "8105",
ptr: new([]byte),
error: "rlp: non-canonical size information for []uint8",
},
{
input: "C3820102",
ptr: new([]byte),
@ -346,10 +356,15 @@ var decodeTests = []decodeTest{
ptr: new([5]byte),
error: "rlp: input string too long for [5]uint8",
},
{
input: "8105",
ptr: new([5]byte),
error: "rlp: non-canonical size information for [5]uint8",
},
// byte array reuse (should be zeroed)
{input: "850102030405", ptr: &sharedByteArray, value: [5]byte{1, 2, 3, 4, 5}},
{input: "8101", ptr: &sharedByteArray, value: [5]byte{1}}, // kind: String
{input: "01", ptr: &sharedByteArray, value: [5]byte{1}}, // kind: String
{input: "850102030405", ptr: &sharedByteArray, value: [5]byte{1, 2, 3, 4, 5}},
{input: "01", ptr: &sharedByteArray, value: [5]byte{1}}, // kind: Byte
{input: "C3010203", ptr: &sharedByteArray, value: [5]byte{1, 2, 3, 0, 0}},
@ -369,9 +384,10 @@ var decodeTests = []decodeTest{
// big ints
{input: "01", ptr: new(*big.Int), value: big.NewInt(1)},
{input: "89FFFFFFFFFFFFFFFFFF", ptr: new(*big.Int), value: veryBigInt},
{input: "820001", ptr: new(big.Int), error: "rlp: non-canonical integer (leading zero bytes) for *big.Int"},
{input: "10", ptr: new(big.Int), value: *big.NewInt(16)}, // non-pointer also works
{input: "C0", ptr: new(*big.Int), error: "rlp: expected input string or byte for *big.Int"},
{input: "820001", ptr: new(big.Int), error: "rlp: non-canonical integer (leading zero bytes) for *big.Int"},
{input: "8105", ptr: new(big.Int), error: "rlp: non-canonical size information for *big.Int"},
// structs
{input: "C0", ptr: new(simplestruct), value: simplestruct{0, ""}},
@ -404,7 +420,7 @@ var decodeTests = []decodeTest{
{input: "80", ptr: new(*uint), value: (*uint)(nil)},
{input: "C0", ptr: new(*uint), value: (*uint)(nil)},
{input: "07", ptr: new(*uint), value: uintp(7)},
{input: "8108", ptr: new(*uint), value: uintp(8)},
{input: "8158", ptr: new(*uint), value: uintp(0x58)},
{input: "C109", ptr: new(*[]uint), value: &[]uint{9}},
{input: "C58403030303", ptr: new(*[][]byte), value: &[][]byte{{3, 3, 3, 3}}},

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