Precision loss

[codehawks-bot]

Precision loss

Severity

Low Risk

Relevant GitHub Links

2023-07-foundry-defi-stablecoin/src/DSCEngine.sol

Lines 330 to 331 in d1c5501

	uint256 collateralAdjustedForThreshold = (collateralValueInUsd * LIQUIDATION_THRESHOLD) / LIQUIDATION_PRECISION;
	return (collateralAdjustedForThreshold * 1e18) / totalDscMinted;

Summary

Precision loss

Vulnerability Details

To avoid loss in precision, perform multiplication before division.

Impact

2023-07-foundry-defi-stablecoin/src/DSCEngine.sol

Lines 330 to 331 in d1c5501

	uint256 collateralAdjustedForThreshold = (collateralValueInUsd * LIQUIDATION_THRESHOLD) / LIQUIDATION_PRECISION;
	return (collateralAdjustedForThreshold * 1e18) / totalDscMinted;

function _calculateHealthFactor(uint256 totalDscMinted, uint256 collateralValueInUsd)
    internal
    pure
    returns (uint256)
{
    if (totalDscMinted == 0) return type(uint256).max;
    uint256 collateralAdjustedForThreshold = (collateralValueInUsd * LIQUIDATION_THRESHOLD) / 100;
    return (collateralAdjustedForThreshold * 1e18) / totalDscMinted;
}

Division before multiplication can lead to truncation and give an incorrect output.

Tools Used

Manual review

Recommendations

    function _calculateHealthFactor(uint256 totalDscMinted, uint256 collateralValueInUsd)
        internal
        pure
        returns (uint256)
    {
        if (totalDscMinted == 0) return type(uint256).max;

        // Multiply first to prevent truncation, then divide
        return (collateralValueInUsd * LIQUIDATION_THRESHOLD * 1e18) / (totalDscMinted * 100);
    }