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

Incorrect scaled contractBalance in RToken#calculateDustAmount() leading to wrong dust calculation

newspacexyz

Summary

The calculateDustAmount() scales contractBalance incorrectly, leading to miscalculations in dust detection.

contractBalance should not be scaled, as it is already the raw token balance of the contract.

This causes incorrect dust amount detection, potentially leading to incorrect fund management.

Vulnerability Details

function calculateDustAmount() public view returns (uint256) {
// Calculate the actual balance of the underlying asset held by this contract
@> uint256 contractBalance = IERC20(_assetAddress).balanceOf(address(this)).rayDiv(ILendingPool(_reservePool).getNormalizedIncome());
​
// Calculate the total real obligations to the token holders
uint256 currentTotalSupply = totalSupply();
​
// Calculate the total real balance equivalent to the total supply
uint256 totalRealBalance = currentTotalSupply.rayMul(ILendingPool(_reservePool).getNormalizedIncome());
// All balance, that is not tied to rToken are dust (can be donated or is the rest of exponential vs linear)
return contractBalance <= totalRealBalance ? 0 : contractBalance - totalRealBalance;
}

Incorrect Scaling of contractBalance

  • contractBalance represents the raw ERC20 balance of the contract.

  • Calling .rayDiv(getNormalizedIncome()) incorrectly scales it down, leading to miscalculations.

Comparison Between Mismatched Values

  • contractBalance (scaled incorrectly) is compared with totalRealBalance (properly scaled).

  • This causes incorrect dust calculations, potentially misreporting the actual dust amount.

This will be damaged with transferAccruedDust().

Impact

transferAccruedDust() doesn't work properly and dust amount will be locked permanently

Tools Used

manual

Recommendations

Remove scaling of contractBalance

function calculateDustAmount() public view returns (uint256) {
// Calculate the actual balance of the underlying asset held by this contract
- uint256 contractBalance = IERC20(_assetAddress).balanceOf(address(this)).rayDiv(ILendingPool(_reservePool).getNormalizedIncome());
+ uint256 contractBalance = IERC20(_assetAddress).balanceOf(address(this));
​
// Calculate the total real obligations to the token holders
uint256 currentTotalSupply = totalSupply();
​
// Calculate the total real balance equivalent to the total supply
uint256 totalRealBalance = currentTotalSupply.rayMul(ILendingPool(_reservePool).getNormalizedIncome());
// All balance, that is not tied to rToken are dust (can be donated or is the rest of exponential vs linear)
return contractBalance <= totalRealBalance ? 0 : contractBalance - totalRealBalance;
}
Updates

Lead Judging Commences

inallhonesty Lead Judge 3 months ago
Submission Judgement Published
Validated
Assigned finding tags:

RToken::calculateDustAmount incorrectly applies liquidity index, severely under-reporting dust amounts and permanently trapping crvUSD in contract

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