Foundry DeFi Stablecoin CodeHawks Audit Contest
Cyfrin
DeFiFoundry
15,000 USDC
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Submission Details
Severity: gas
Valid

Gas/QA report

rotcivegaf

Gas report

[G-01] Don't overcheck

The following are double checked since they are validated in: OZ ERC20

File: src/DecentralizedStableCoin.sol
​
47: uint256 balance = balanceOf(msg.sender);
​
51: if (balance < _amount) {
52: revert DecentralizedStableCoin__BurnAmountExceedsBalance();
53: }
​
58: if (_to == address(0)) {
59: revert DecentralizedStableCoin__NotZeroAddress();
60: }

[G-02] Save value to avoid SLOAD

File: src/DSCEngine.sol
​
/// @audit: Save `tokenAddresses[i]` in local var
119: s_priceFeeds[tokenAddresses[i]] = priceFeedAddresses[i];
120: s_collateralTokens.push(tokenAddresses[i]);

[G-03] Add unchecked{} in operations where the operands cannot over/underflow

File: src/DSCEngine.sol
​
251: uint256 bonusCollateral = (tokenAmountFromDebtCovered * LIQUIDATION_BONUS) / LIQUIDATION_PRECISION;
​
252: uint256 totalCollateralToRedeem = tokenAmountFromDebtCovered + bonusCollateral;

[G-04] constructor could be marked as payable

File: src/DecentralizedStableCoin.sol
​
44: constructor() ERC20("DecentralizedStableCoin", "DSC") {}
File: src/DSCEngine.sol
​
112: constructor(address[] memory tokenAddresses, address[] memory priceFeedAddresses, address dscAddress) {

[G-05] Implement a burnFrom function to save approve transaction

Since the DSCEngine contract is the owner of the DecentralizedStableCoin, it could implement the burnFrom function to burn the tokens directly, saving an approve transaction for the user:

@@ -40,6 +40,7 @@ contract DecentralizedStableCoin is ERC20Burnable, Ownable {
error DecentralizedStableCoin__MustBeMoreThanZero();
error DecentralizedStableCoin__BurnAmountExceedsBalance();
error DecentralizedStableCoin__NotZeroAddress();
+ error DecentralizedStableCoin__BlockFunction();
​
constructor() ERC20("DecentralizedStableCoin", "DSC") {}
​
@@ -54,6 +55,10 @@ contract DecentralizedStableCoin is ERC20Burnable, Ownable {
super.burn(_amount);
}
​
+ function burnFrom(address account, uint256 amount) public override onlyOwner {
+ _burn(account, amount);
+ }
+
function mint(address _to, uint256 _amount) external onlyOwner returns (bool) {
if (_to == address(0)) {
revert DecentralizedStableCoin__NotZeroAddress();
@@ -271,12 +271,7 @@ contract DSCEngine is ReentrancyGuard {
*/
function _burnDsc(uint256 amountDscToBurn, address onBehalfOf, address dscFrom) private {
s_DSCMinted[onBehalfOf] -= amountDscToBurn;
- bool success = i_dsc.transferFrom(dscFrom, address(this), amountDscToBurn);
- // This conditional is hypothtically unreachable
- if (!success) {
- revert DSCEngine__TransferFailed();
- }
- i_dsc.burn(amountDscToBurn);
+ i_dsc.burnFrom(dscFrom, amountDscToBurn);
}

Non-critical

[N‑01] Typo

File: src/DSCEngine.sol
​
/// @audit: `Algoritmically` to `Algorithmically`
040: * - Algoritmically Stable

[N-02] Non-library/interface files should use fixed compiler versions, not floating ones

File: src/DSCEngine.sol
​
24:pragma solidity ^0.8.18;
File: src/DecentralizedStableCoin.sol
​
24:pragma solidity ^0.8.18;

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