Fee on transfer collaterals

[codehawks-bot]

Fee on transfer collaterals

Severity

Medium Risk

Summary

There are tokens which charge fees when moving them and of they are used as collaterals, the protocol won't work properly

Vulnerability Details

For instance in DSCEngine.sol

function depositCollateral(address tokenCollateralAddress, uint256 amountCollateral)
        public
        moreThanZero(amountCollateral)
        isAllowedToken(tokenCollateralAddress)
        nonReentrant
    {
        s_collateralDeposited[msg.sender][tokenCollateralAddress] += amountCollateral;
        emit CollateralDeposited(msg.sender, tokenCollateralAddress, amountCollateral);
        bool success = IERC20(tokenCollateralAddress).transferFrom(msg.sender, address(this), amountCollateral);
        if (!success) {
            revert DSCEngine__TransferFailed();
        }
    }

The following line will lead to the protocol receiving less tokens than expected bool success = IERC20(tokenCollateralAddress).transferFrom(msg.sender, address(this), amountCollateral);

Impact

The protocol will have accounting errors

Tools Used

Manual review

Recommendations

Consider choosing collateral tokens that do not support transfer fees or get the actual received amount by calculating the difference of token balance before and after the transfer.