LibFeeCalculator Static Analysis Findings

LFC-01S: Potential Loss of Precision

Description:

The accrue function reverses the division performed on the delta between feesAccrued and previousAccrued using a multiplication which can cause a truncation / loss of precision at most equal to members - 1.

Example:

Copy
111function accrue(FeeCalculator storage _fc) internal returns (uint256) {
112    uint256 members = LibGovernance.membersCount();
113    uint256 amount = (_fc.feesAccrued - _fc.previousAccrued) / members;
114    _fc.previousAccrued += amount * members;
115    _fc.accumulator = _fc.accumulator + amount;
116
117    return _fc.accumulator;
118}

Recommendation:

We advise the delta to be stored to a dedicated variable that is then used for calculating the division as well as incrementing previousAccrued. This will also reduce the gas cost of the function.

Alleviation:

The Limechain team has stated that they prefer to retain the current solution in place. While it suffers from precision loss, this loss is carried over until the next distribution guaranteeing that the loss of precision will at some point in time be correctly distributed should the numbers be wholly divisible. As such, we consider this exhibit null.