ZeroDivisionError in CONCAT

[sam-xif]

Summary of the problem

Hello manticore community,

I am working as part of a research team developing a code analysis tool for Python. One of the issues the tool discovered in manticore's codebase is that core.smtlib.operators.CONCAT has the potential to throw a ZeroDivisionError. The ZeroDivisionError is caused by an empty *args argument list.

If you are interested in learning more about the tool and how it found this issue, let me know down in the comments, or you can contact me at xifaras.s@northeastern.edu. We are primarily curious about whether you find that this issue is legitimate and worth reporting and fixing. If not, we would be interested in understanding why.

Thank you for your consideration!

-Sam

Manticore version

Latest master (commit hash: 8861005)

Python version

Python 3.8

OS / Environment

Linux (kernel version 5.10.218)

Dependencies

N/A

Step to reproduce the behavior

Call CONCAT with only a single argument.

Expected behavior

It should be impossible to pass an empty *args list to this function.

Actual behavior

Traceback:

Traceback (most recent call last):
  ...
  File ".../repos/manticore/manticore/core/smtlib/operators.py", line 157, in CONCAT
    arg_size = total_size // len(args)
ZeroDivisionError: integer division or modulo by zero