broken clamps in initcode

[charles-cooper]

Version Information

• vyper Version (output of vyper --version): v0.2.16

What's your issue about?

Clampers for __init__ bytestrings use calldata (which is always 0 for constructors). In other words, they always validate the constructor arguments even if they are borked.

Example contract:

foo: Bytes[20]

@external
def __init__(x: Bytes[20]):
    self.foo = x

Constructor LLL:

  [codecopy, 320, ~codelen, 32],
  [codecopy, 352, [add, ~codelen, [codeload, ~codelen]], 52],
  [assert, [le, [calldataload, [add, 4, [codeload, ~codelen]]], 20]], # BYTESTRING CLAMP IS HERE - always returns true
  # Line 6
  [with,
    _pos,
    352 <x>,
    /* copy byte slice src: _pos dst: 0 <self.foo> */ 
    [with,
      _pos,
      _pos,
      [with,
        _opos,
        0 <self.foo>,
        [with,
          _actual_len,
          [add, [mload, _pos], 32],
          [repeat,
            288,
            0,
            2,
            [seq,
              [if, [gt, [mul, 32, [mload, 288]], _actual_len], break],
              [sstore,
                [add, _opos, [mload, 288]],
                [mload, [add, _pos, [mul, 32, [mload, 288]]]]]]]]]]],

How can it be fixed?

Fill this in if you know how to fix it.

[charles-cooper]

fixed in #2447