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

The user receives higher debt amount than expected

rampage

Summary

An incorrect debt amount calculation in DebtToken.sol will cause users to receive more debt than they should, as the protocol adds the index-adjusted balance increase to the new debt amount being minted.

Root Cause

In DebtToken.sol the protocol incorrectly adds balanceIncrease to the new debt amount during minting, which results in users receiving more debt than they should.

function mint(
address user,
address onBehalfOf,
uint256 amount,
uint256 index
) external override onlyReservePool returns (bool, uint256, uint256) {
if (user == address(0) || onBehalfOf == address(0)) revert InvalidAddress();
if (amount == 0) {
return (false, 0, totalSupply());
}
​
uint256 amountScaled = amount.rayDiv(index);
if (amountScaled == 0) revert InvalidAmount();
​
uint256 scaledBalance = balanceOf(onBehalfOf);
bool isFirstMint = scaledBalance == 0;
​
uint256 balanceIncrease = 0;
if (_userState[onBehalfOf].index != 0 && _userState[onBehalfOf].index < index) {
-> balanceIncrease = scaledBalance.rayMul(index) - scaledBalance.rayMul(_userState[onBehalfOf].index);
}
​
_userState[onBehalfOf].index = index.toUint128();
​
162-> uint256 amountToMint = amount + balanceIncrease;
​
_mint(onBehalfOf, amountToMint.toUint128());
​
emit Transfer(address(0), onBehalfOf, amountToMint);
emit Mint(user, onBehalfOf, amountToMint, balanceIncrease, index);
​
return (scaledBalance == 0, amountToMint, totalSupply());
}

Impact

Users receive a higher debt amount than they should due to the incorrect addition of balanceIncrease to the minted amount. This impacts all users who mint debt tokens when their index has increased since their last interaction.

Mitigation

The mint() function should be modified to only mint the new debt amount without adding the balanceIncrease. The index adjustment should be handled separately from the minting process.

Updates

Lead Judging Commences

inallhonesty Lead Judge 7 months ago
Submission Judgement Published
Validated
Assigned finding tags:

DebtToken::mint miscalculates debt by applying interest twice, inflating borrow amounts and risking premature liquidations

inallhonesty Lead Judge 7 months ago
Submission Judgement Published
Validated
Assigned finding tags:

DebtToken::mint miscalculates debt by applying interest twice, inflating borrow amounts and risking premature liquidations

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