Calldatasize constraints

When there is a constraint on some calldata[x] != 0 then there should be a constraint that the calldatasize > x

Take the example by Chofhe from discord( @nbanmp ):

contract Suicide {
  uint256 isAllowed = 0;

  function kill(address addr, uint256 isAllowed) {
    require(isAllowed == 42);
    require(msg.data.length == 4);
    selfdestruct(addr);
  }
}

Where mythril now reports a false positive

Proposed solution

Add the following constraint on calldataload:

# given variables: index, caldataload[index], calldatasize
Or(calldataload[index] == 0, index < calldatasize)

Good first issue

This issue is labeled as a good first issue. Hop by on our discord server if you’d like to contribute!

[nbanmp]

@gitcoinbot https://github.com/ConsenSys/mythril-classic/pull/557 now correctly achieves this.

[gitcoinbot]

Issue Status: 1. Open 2. Started 3. Submitted 4. Done

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The funding of 0.6 ETH (122.81 USD @ $204.68/ETH) attached to this issue has been approved & issued to @nbanmp.

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