[Audit Fix] `ElasticMath.capitalDelta` missing `SafeMath.sub` use

[dmvt]

Use of Safemath.sub is missing in the function join, call to ElasticMath.capitalDelta

Risk Rating

1 (low)

Vulnerability Details

A subtraction is made without using Safemath in the call to function ElasticMath.capitalDelta:

ElasticDAO.sol:

function join(uint256 _deltaLambda)
    uint256 capitalDelta =
      ElasticMath.capitalDelta(
        // the current totalBalance of the DAO is inclusive of msg.value,
        // capitalDelta is to be calculated without the msg.value
        address(this).balance - msg.value,
        tokenContract.totalSupply()
      );

Impact

Although in practice this will not result in a negative value, this happens to be one of the more dangerous points because ETH is being handled here.

Tools Used

Remix

Recommended Mitigation Steps

Use Safemath.sub

Definition of Done

• above code uses SafeMath.sub