Submission Details
Severity:
Fee on transfer token errors
Summary
As arbitrary ERC20 tokens can be passed, the amount here should be calculated every time to take into consideration a possible fee-on-transfer or deflation.
Vulnerability Details
For instance in borrow() function, the following will lead to accounting errors
// transfer fees
IERC20(loan.loanToken).transfer(feeReceiver, fees);
// transfer the loan tokens from the pool to the borrower
IERC20(loan.loanToken).transfer(msg.sender, debt - fees);
// transfer the collateral tokens from the borrower to the contract
IERC20(loan.collateralToken).transferFrom(
msg.sender,
address(this),
collateral
);
Impact
If a pool is using fee on transfer tokens for loans or collateral, then when using the borrow() function , less tokens will be sent to protocol causing accounting errors.
Tools Used
Manual review
Recommendations
Check the balance before and after the transfer to take into account the Fees-On-Transfer.
Prize pool breakdown
Total prize
20,000 USDC
nSLOC
70628 USDC / LOC
18,000 USDC
2,000 USDC
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