Core Contracts
Regnum Aurum Acquisition Corp
HardhatReal World AssetsNFT
77,280 USDC
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Submission Details
Severity: medium
Valid

Incorrect burn parameters in withdraw function

Author Revealed upon completion

Summary

The withdraw function() contains a vulnerability due to incorrect return parameters from the burn function in the RToken contract. This issue causes inconsistencies in accounting and event emissions, potentially leading to miscalculations in liquidity.

Vulnerability Details

https://github.com/Cyfrin/2025-02-raac/blob/89ccb062e2b175374d40d824263a4c0b601bcb7f/contracts/core/pools/LendingPool/LendingPool.sol#L252

In the Withdraw() of lendingPool contract, it calls the ReserveLibrary.withdraw

// Perform the withdrawal through ReserveLibrary
(uint256 amountWithdrawn, uint256 amountScaled, uint256 amountUnderlying) = ReserveLibrary.withdraw(
reserve, // ReserveData storage
rateData, // ReserveRateData storage
amount, // Amount to withdraw
msg.sender // Recipient
);
​

The ReserveLibrary.withdraw() calls RToken.burn()

https://github.com/Cyfrin/2025-02-raac/blob/89ccb062e2b175374d40d824263a4c0b601bcb7f/contracts/libraries/pools/ReserveLibrary.sol#L365

function withdraw(
ReserveData storage reserve,
ReserveRateData storage rateData,
uint256 amount,
address recipient
) internal returns (uint256 amountWithdrawn, uint256 amountScaled, uint256 amountUnderlying) {
if (amount < 1) revert InvalidAmount();
​
// Update the reserve interests
updateReserveInterests(reserve, rateData);
​
// Burn RToken from the recipient - will send underlying asset to the recipient
(uint256 burnedScaledAmount, uint256 newTotalSupply, uint256 amountUnderlying) = IRToken(reserve.reserveRTokenAddress).burn(
recipient, // from
recipient, // receiverOfUnderlying
amount, // amount
reserve.liquidityIndex // index
);// audit-issues: it calls the burn function
amountWithdrawn = burnedScaledAmount;
// Update the total liquidity and interest rates
updateInterestRatesAndLiquidity(reserve, rateData, 0, amountUnderlying);
​
emit Withdraw(recipient, amountUnderlying, burnedScaledAmount);
​
return (amountUnderlying, burnedScaledAmount, amountUnderlying);
}

Here is the burn function in the RToken contract

https://github.com/Cyfrin/2025-02-raac/blob/89ccb062e2b175374d40d824263a4c0b601bcb7f/contracts/core/tokens/RToken.sol#L154C4-L185C6

function burn(
address from,
address receiverOfUnderlying,
uint256 amount,
uint256 index
) external override onlyReservePool returns (uint256, uint256, uint256) {
if (amount == 0) {
return (0, totalSupply(), 0);
}
​
uint256 userBalance = balanceOf(from);
​
_userState[from].index = index.toUint128();
​
if(amount > userBalance){
amount = userBalance;
}
​
uint256 amountScaled = amount.rayMul(index);
​
_userState[from].index = index.toUint128();
​
_burn(from, amount.toUint128());
​
if (receiverOfUnderlying != address(this)) {
IERC20(_assetAddress).safeTransfer(receiverOfUnderlying, amount);
}
​
emit Burn(from, receiverOfUnderlying, amount, index);
​
return (amount, totalSupply(), amount);//audit-issue:it returns amount twice leaving out amountScaled
}

In the burn(), it incorrectly returns "return (amount, totalSupply(), amount)" instead of "return (amountScaled, totalSupply(), amount)"

This will in turn affect the return values from ReserveLibrary.withdraw() and in turn return values of Withdraw() from lendingpool contract which will lead to inconsistencies

Impact

Tools Used

Manual review

Recommendations

Fix the ordering of the parameters from burn() in RToken contract

Updates

Lead Judging Commences

inallhonesty Lead Judge 16 days ago
Submission Judgement Published
Validated
Assigned finding tags:

RToken::burn returns incorrect underlying asset amount (amount instead of amountScaled), leading to wrong interest rate calculations

inallhonesty Lead Judge 16 days ago
Submission Judgement Published
Validated
Assigned finding tags:

RToken::burn returns incorrect underlying asset amount (amount instead of amountScaled), leading to wrong interest rate calculations

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