Submission Details
Severity:
The protocol doesn't have support for fee on transfer type of ERC20 tokens
Summary
The protocol doesn't have support for fee on transfer type of ERC20 tokens
Vulnerability Details
In the following places in Lender.sol we see this problem:
152: IERC20(p.loanToken).transferFrom(
159: IERC20(p.loanToken).transfer(
187: IERC20(pools[poolId].loanToken).transferFrom(
203: IERC20(pools[poolId].loanToken).transfer(msg.sender, amount);
267: IERC20(loan.loanToken).transfer(feeReceiver, fees);
269: IERC20(loan.loanToken).transfer(msg.sender, debt - fees);
271: IERC20(loan.collateralToken).transferFrom(
317: IERC20(loan.loanToken).transferFrom(
323: IERC20(loan.loanToken).transferFrom(
329: IERC20(loan.collateralToken).transfer(
403: IERC20(loan.loanToken).transfer(feeReceiver, protocolInterest);
505: IERC20(loan.loanToken).transfer(feeReceiver, protocolInterest);
563: IERC20(loan.collateralToken).transfer(feeReceiver, govFee);
565: IERC20(loan.collateralToken).transfer(
642: IERC20(loan.loanToken).transferFrom(
651: IERC20(loan.loanToken).transfer(feeReceiver, fee);
653: IERC20(loan.loanToken).transfer(msg.sender, debt - debtToPay - fee);
656: IERC20(loan.loanToken).transfer(feeReceiver, protocolInterest);
663: IERC20(loan.collateralToken).transferFrom(
670: IERC20(loan.collateralToken).transfer(
Impact
Some ERC20 token implementations have a fee that is charged on each token transfer. This means that the transferred amount isn't exactly what the receiver will get.
Tools Used
Visual Studio Code
Recommendations
Improve support for a fee on transfer type of ERC20. When pulling funds from the user using transferFrom() and transfer() the usual approach is to compare balances pre/post transfer.
Prize pool breakdown
Total prize
20,000 USDC
nSLOC
70628 USDC / LOC
18,000 USDC
2,000 USDC
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