ak1 - Carousel.sol : Incorrect fee is used in `minRequiredDeposit(_assets)` used for `deposit` and `depositETH`

[sherlock-admin]

ak1

medium

Carousel.sol : Incorrect fee is used in minRequiredDeposit(_assets) used for deposit and depositETH

Summary

Carousel.sol has two types of fee, 1.)relayerFee ( should be relayerFee < 10000). 2.) depositFee ( should be depositFee > 250)

relayer fee is used in que based deposit whereas deposit fee is used in direct deposit of assets.

Using the realer fee to decide the direct deposit could be incorrect.

Vulnerability Detail

when we see the deposit and depositETH functions, both are having minRequiredDeposit(_assets) modifier which has the relayer fee based condition,

modifier minRequiredDeposit(uint256 _assets) {
    if (_assets < relayerFee) revert MinDeposit();
    _;
}

when we look at the _deposit, ti has the _calculateFeePercent to calculate fee incase deposit fee is greater than zero.

inside the function _calculateFeePercent, deposit fee is used to calculate the fee.

function _calculateFeePercent(int256 minX, int256 maxX)
    internal
    view
    returns (uint256 _y)
{
    /**
     * Two Point Form
     * https://www.cuemath.com/geometry/two-point-form/
     * https://ethereum.stackexchange.com/a/143172
     */
    // minY will always be 0 thats why is (maxY - minY) shorten to maxY
    int256 maxY = int256(depositFee) * int256(FixedPointMathLib.WAD); -----------------> audit find
    _y = uint256( // cast to uint256
        ((((maxY) / (maxX - minX)) * (int256(block.timestamp) - maxX)) +
            maxY) / (int256(FixedPointMathLib.WAD)) // two point math // scale down
    );
}

Impact

Incorrect fee value is used to decide the deposit and depositETH. when we look at the the below check in constructor,

    if (_data.relayerFee < 10000) revert RelayerFeeToLow();
    if (_data.depositFee > 250) revert BPSToHigh();

having the check < 10000 for relayerr fee, the condition for deposit fee is violated.

Code Snippet

https://github.com/sherlock-audit/2023-03-Y2K/blob/main/Earthquake/src/v2/Carousel/Carousel.sol#L78-L118

https://github.com/sherlock-audit/2023-03-Y2K/blob/main/Earthquake/src/v2/Carousel/Carousel.sol#L470-L489

Tool used

Manual Review

Recommendation

Use another modifier like deposit fee based, to decide the minimum deposit for direct deposit such as deposit and depsoitETH