Merge pull request #153 from shortdoom/fix-detector-fail-develop

fix: object of type NoneType has no len() - PotentialArithmOverflow detector fail

slitherin/detectors/potential_arith_overflow.py

@@ -86,7 +86,7 @@ def _find_vulnerable_expressions(self, fun: Function) -> list:
  errors.extend(response_errors)
  if has_problems:
  final_results.append((node, str(irs[-1].lvalue._type), errors))
- if len(irs) > 0 and isinstance(irs[-1], ops.Return) and len(fun.return_type) == 1 and str(fun.return_type[0]) in INT_TYPES: # @todo currently works only with single returns
+ if len(irs) > 0 and isinstance(irs[-1], ops.Return) and fun.return_type is not None and len(fun.return_type) == 1 and str(fun.return_type[0]) in INT_TYPES: # @todo currently works only with single returns
  expected_bits_cut = str(fun.return_type[0]).removeprefix("uint").removeprefix("int")
  expected_bits = int(256 if not expected_bits_cut else expected_bits_cut)
  has_problems = False
@@ -115,4 +115,4 @@ def _detect(self) -> List[Output]:
  for (op, op_ret_type) in op_with_ret_type:
  info += ["\t\t`", str(op), f"` returns {op_ret_type}, but the type of the resulting expression is {node_final_type}.", "\n"]
  res.append(self.generate_result(info))
- return res
+ return res