Foundation Drop contest - robee's results

Require with empty message

The following requires are with empty messages. This is very important to add a message for any require. So the user has enough information to know the reason of failure.

Code instances:

    Solidity file: WETH9.sol, In line 55 with Empty Require message.
    Solidity file: WETH9.sol, In line 29 with Empty Require message.

Not verified input

external / public functions parameters should be validated to make sure the address is not 0. Otherwise if not given the right input it can mistakenly lead to loss of user funds.

Code instances:

    FETH.sol.approve spender
    WETH9.sol.transfer dst
    FETHMarketMock.sol.marketChangeLockup unlockFrom
    MinterRole.sol.grantMinter account

Hardcoded WETH

WETH address is hardcoded but it may differ on other chains, e.g. Polygon, so make sure to check this before deploying and update if necessary You should consider injecting WETH address via the constructor. (previous issue: https://github.com/code-423n4/2021-10-ambire-findings/issues/54)

Code instance:

    Hardcoded weth address in FETH.sol

Init frontrun

Most contracts use an init pattern (instead of a constructor) to initialize contract parameters. Unless these are enforced to be atomic with contact deployment via deployment script or factory contracts, they are susceptible to front-running race conditions where an attacker/griefer can front-run (cannot access control because admin roles are not initialized) to initially with their own (malicious) parameters upon detecting (if an event is emitted) which the contract deployer has to redeploy wasting gas and risking other transactions from interacting with the attacker-initialized contract.

Many init functions do not have an explicit event emission which makes monitoring such scenarios harder. All of them have re-init checks; while many are explicit some (those in auction contracts) have implicit reinit checks in initAccessControls() which is better if converted to an explicit check in the main init function itself. (details credit to: https://github.com/code-423n4/2021-09-sushimiso-findings/issues/64) The vulnerable initialization functions in the codebase are:

Code instances:

    NFTDropCollection.sol, initialize, 120
    NFTDropMarket.sol, initialize, 100
    NFTCollection.sol, initialize, 105
    SequentialMintCollectionMock.sol, initializeWithModifier, 10
    PercentSplitETH.sol, initialize, 129
    NFTCollectionFactory.sol, initialize, 192
    FoundationTreasury.sol, initialize, 66

Named return issue

Users can mistakenly think that the return value is the named return, but it is actually the actualreturn statement that comes after. To know that the user needs to read the code and is confusing. Furthermore, removing either the actual return or the named return will save gas.

Code instances:

    BasicERC721.sol, balanceOf
    FETH.sol, transferFrom
    FETH.sol, marketLockupFor

In the following public update functions no value is returned

In the following functions no value is returned, due to which by default value of return will be 0. We assumed that after the update you return the latest new value. (similar issue here: https://github.com/code-423n4/2021-10-badgerdao-findings/issues/85).

Code instances:

    NFTDropCollection.sol, updateMaxTokenId
    NFTCollectionFactory.sol, adminUpdateNFTCollectionImplementation
    NFTCollectionFactory.sol, adminUpdateNFTDropCollectionImplementation
    NFTCollection.sol, updateMaxTokenId
    NFTCollection.sol, updateBaseURI
    NFTDropCollection.sol, updatePreRevealContent

Never used parameters

Those are functions and parameters pairs that the function doesn't use the parameter. In case those functions are external/public this is even worst since the user is required to put value that never used and can misslead him and waste its time.

Code instances:

    OZERC165Checker.sol: function supportsERC165InterfaceUnchecked parameter account isn't used. (supportsERC165InterfaceUnchecked is internal)
    FETHMarketMock.sol: function marketChangeLockup parameter unlockAmount isn't used. (marketChangeLockup is external)
    FETHMarketMock.sol: function marketLockupFor parameter amount isn't used. (marketLockupFor is public)
    MockRoyaltyRegistry.sol: function setRoyaltyLookupAddress parameter tokenAddress isn't used. (setRoyaltyLookupAddress is external)
    FETHMarketMock.sol: function marketChangeLockup parameter depositFor isn't used. (marketChangeLockup is external)
    FETHMarketMock.sol: function marketChangeLockup parameter depositAmount isn't used. (marketChangeLockup is external)
    SendValueWithFallbackWithdraw.sol: function _sendValueWithFallbackWithdraw parameter gasLimit isn't used. (_sendValueWithFallbackWithdraw is internal)
    FETHMarketMock.sol: function marketLockupFor parameter account isn't used. (marketLockupFor is public)
    FETHMarketMock.sol: function marketChangeLockup parameter unlockExpiration isn't used. (marketChangeLockup is external)
    FETHMarketMock.sol: function marketChangeLockup parameter unlockFrom isn't used. (marketChangeLockup is external)
    MockRoyaltyRegistry.sol: function setRoyaltyLookupAddress parameter royaltyAddress isn't used. (setRoyaltyLookupAddress is external)

Check transfer receiver is not 0 to avoid burned money

Transferring tokens to the zero address is usually prohibited to accidentally avoid "burning" tokens by sending them to an unrecoverable zero address.

Code instances:

    https://github.com/code-423n4/2022-08-foundation/tree/main/contracts/mocks/BasicERC721.sol#L263
    https://github.com/code-423n4/2022-08-foundation/tree/main/contracts/FETH.sol#L383
    https://github.com/code-423n4/2022-08-foundation/tree/main/contracts/PercentSplitETH.sol#L236
    https://github.com/code-423n4/2022-08-foundation/tree/main/contracts/FETH.sol#L267
    https://github.com/code-423n4/2022-08-foundation/tree/main/contracts/mocks/BasicERC721.sol#L244

Missing commenting

    The following functions are missing commenting as describe below:
    

Code instance:

    FETHNode.sol, _tryUseFETHBalance (internal), parameters totalAmount, shouldRefundSurplus not commented

Add a timelock

To give more trust to users: functions that set key/critical variables should be put behind a timelock.

Code instances:

    https://github.com/code-423n4/2022-08-foundation/tree/main/contracts/mocks/RoyaltyRegistry/MockRoyaltyRegistry.sol#L9
    https://github.com/code-423n4/2022-08-foundation/tree/main/contracts/mocks/FETHMarketMock.sol#L14
    https://github.com/code-423n4/2022-08-foundation/tree/main/contracts/mocks/BasicERC721.sol#L81

Unsafe Cast

use openzeppilin's safeCast in:

Code instances:

    https://github.com/code-423n4/2022-08-foundation/tree/main/contracts/FETH.sol#L514 : unsafe cast uint32(escrowIndex)
    https://github.com/code-423n4/2022-08-foundation/tree/main/contracts/FETH.sol#L615 : unsafe cast uint96(amount)
    https://github.com/code-423n4/2022-08-foundation/tree/main/contracts/FETH.sol#L498 : unsafe cast uint96(amount)
    https://github.com/code-423n4/2022-08-foundation/tree/main/contracts/FETH.sol#L393 : unsafe cast uint96(amount)

transfer return value of a general ERC20 is ignored

Need to use safeTransfer instead of transfer. As there are popular tokens, such as USDT that transfer/trasnferFrom method doesn’t return anything. The transfer return value has to be checked (as there are some other tokens that returns false instead revert), that means you must

1. Check the transfer return value Another popular possibility is to add a whiteList. Those are the appearances (solidity file, line number, actual line):

Code instances:

    PercentSplitETH.sol, 245 (_splitERC20Tokens), try erc20Contract.transfer(_shares[0].recipient, amountToSend) {
    PercentSplitETH.sol, 236 (_splitERC20Tokens), try erc20Contract.transfer(share.recipient, amountToSend) {

State variables that could be set immutable

In the following files there are state variables that could be set immutable to save gas.

Code instances:

    versionNFTCollection in NFTCollectionFactory.sol
    paymentAddress in NFTDropCollection.sol

Unused state variables

Unused state variables are gas consuming at deployment (since they are located in storage) and are a bad code practice. Removing those variables will decrease deployment gas cost and improve code quality. This is a full list of all the unused storage variables we found in your code base.

Code instances:

    AdminRole.sol, __gap
    OZAccessControlUpgradeable.sol, __gap
    NFTDropMarketFixedPriceSale.sol, __gap
    MarketSharedCore.sol, __gap
    WETH9.sol, symbol
    SendValueWithFallbackWithdraw.sol, __gap_was_pendingWithdrawals
    WETH9.sol, name
    Gap10000.sol, __gap
    WETH9.sol, decimals
    NFTDropMarketCore.sol, __gap
    CollateralManagement.sol, __gap
    FoundationTreasuryNode.sol, __gap_was_treasury

Unused declared local variables

Unused local variables are gas consuming, since the initial value assignment costs gas. And are a bad code practice. Removing those variables will decrease the gas cost and improve code quality. This is a full list of all the unused storage variables we found in your code base.

Code instance:

    OZERC165Checker.sol, supportsERC165InterfaceUnchecked, encodedParams

Unnecessary array boundaries check when loading an array element twice

There are places in the code (especially in for-each loops) that loads the same array element more than once. 
In such cases, only one array boundaries check should take place, and the rest are unnecessary.
Therefore, this array element should be cached in a local variable and then be loaded
again using this local variable, skipping the redundant second array boundaries check: 

Code instance:

    PercentSplitETH.sol.getShares - double load of _shares[i]

Caching array length can save gas

Caching the array length is more gas efficient. This is because access to a local variable in solidity is more efficient than query storage / calldata / memory. We recommend to change from:

for (uint256 i=0; i<array.length; i++) { ... }

to:

uint len = array.length  
for (uint256 i=0; i<len; i++) { ... }

Code instances:

    PercentSplitETH.sol, shares, 320
    PercentSplitETH.sol, _shares, 115

Prefix increments are cheaper than postfix increments

Prefix increments are cheaper than postfix increments. Further more, using unchecked {++x} is even more gas efficient, and the gas saving accumulates every iteration and can make a real change There is no risk of overflow caused by increamenting the iteration index in for loops (the ++i in for (uint256 i = 0; i < numIterations; ++i)). But increments perform overflow checks that are not necessary in this case. These functions use not using prefix increments (++x) or not using the unchecked keyword:

Code instances:

    just change to unchecked: PercentSplitETH.sol, i, 320
    just change to unchecked: PercentSplitETH.sol, i, 115

Unnecessary index init

In for loops you initialize the index to start from 0, but it already initialized to 0 in default and this assignment cost gas. It is more clear and gas efficient to declare without assigning 0 and will have the same meaning:

Code instances:

    PercentSplitETH.sol, 320
    PercentSplitETH.sol, 115

Storage double reading. Could save SLOAD

Reading a storage variable is gas costly (SLOAD). In cases of multiple read of a storage variable in the same scope, caching the first read (i.e saving as a local variable) can save gas and decrease the overall gas uses. The following is a list of functions and the storage variables that you read twice:

Code instance:

    PercentSplitETH.sol: BASIS_POINTS is read twice in initialize

Unnecessary default assignment

Unnecessary default assignments, you can just declare and it will save gas and have the same meaning.

Code instance:

    BasicERC721WithoutOwnerOfRevert.sol (L#18) : uint256 private id = 0; 

Use bytes32 instead of string to save gas whenever possible

Use bytes32 instead of string to save gas whenever possible.
String is a dynamic data structure and therefore is more gas consuming then bytes32.

Code instances:

    FETH.sol (L135), string public constant symbol = "FETH"; 
    WETH9.sol (L6), string public name = "Wrapped Ether";
    WETH9.sol (L7), string public symbol = "WETH";
    FETH.sol (L130), string public constant name = "Foundation ETH"; 

Short the following require messages

The following require messages are of length more than 32 and we think are short enough to short them into exactly 32 characters such that it will be placed in one slot of memory and the require function will cost less gas. The list:

Code instances:

    Solidity file: BasicERC721.sol, In line 263, Require message length to shorten: 37, The message: ERC721: transfer from incorrect owner
    Solidity file: PercentSplitETH.sol, In line 148, Require message length to shorten: 35, The message: Split: Total amount must equal 100%
    Solidity file: NFTDropCollection.sol, In line 130, Require message length to shorten: 40, The message: NFTDropCollection: `_symbol` must be set
    Solidity file: NFTDropCollection.sol, In line 179, Require message length to shorten: 38, The message: NFTDropCollection: Exceeds max tokenId
    Solidity file: NFTCollection.sol, In line 263, Require message length to shorten: 35, The message: NFTCollection: tokenCID is required
    Solidity file: NFTDropCollection.sol, In line 238, Require message length to shorten: 39, The message: NFTDropCollection: use `reveal` instead
    Solidity file: NFTCollection.sol, In line 264, Require message length to shorten: 37, The message: NFTCollection: NFT was already minted
    Solidity file: PercentSplitETH.sol, In line 191, Require message length to shorten: 33, The message: Split: ERC20 tokens must be split
    Solidity file: PercentSplitETH.sol, In line 136, Require message length to shorten: 35, The message: Split: Share must be less than 100%
    Solidity file: NFTCollectionFactory.sol, In line 262, Require message length to shorten: 40, The message: NFTCollectionFactory: Symbol is required
    Solidity file: BasicERC721.sol, In line 59, Require message length to shorten: 33, The message: ERC721: approval to current owner
    Solidity file: BasicERC721.sol, In line 264, Require message length to shorten: 36, The message: ERC721: transfer to the zero address

Use != 0 instead of > 0

Using != 0 is slightly cheaper than > 0. (see https://github.com/code-423n4/2021-12-maple-findings/issues/75 for similar issue)

Code instances:

    NFTDropMarketFixedPriceSale.sol, 183: change 'balance > 0' to 'balance != 0'
    WETH9.sol, 55: change 'balance > 0' to 'balance != 0'
    WETH9.sol, 29: change 'balance > 0' to 'balance != 0'
    LockedBalance.sol, 113: change 'balance > 0' to 'balance != 0'
    NFTDropCollection.sol, 131: change '_maxTokenId > 0' to '_maxTokenId != 0'

Use unchecked to save gas for certain additive calculations that cannot overflow

You can use unchecked in the following calculations since there is no risk to overflow:

Code instances:

    FETH.sol (L#572) - expiration = lockupDuration + block.timestamp.ceilDiv(lockupInterval) * lockupInterval;
    FETH.sol (L#765) - if (escrow.expiration >= block.timestamp && escrow.totalAmount != 0) { ++lockedCount;

Consider inline the following functions to save gas

You can inline the following functions instead of writing a specific function to save gas.
(see https://github.com/code-423n4/2021-11-nested-findings/issues/167 for a similar issue.)

Code instances

    OZAccessControlUpgradeable.sol, getRoleMemberCount, { return _roles[role].members.length(); }
    BasicERC721.sol, _exists, { return _owners[tokenId] != address(0); }
    OZAccessControlUpgradeable.sol, getRoleMember, { return _roles[role].members.at(index); }
    OZAccessControlUpgradeable.sol, hasRole, { return _roles[role].members.contains(account); }
    NFTCollectionFactory.sol, _getSalt, { return keccak256(abi.encodePacked(creator, nonce)); }
    AddressLibrary.sol, callAndReturnContractAddress, { return callAndReturnContractAddress(call.target, call.callData); }

Inline one time use functions

The following functions are used exactly once. Therefore you can inline them and save gas and improve code clearness.

Code instances:

    NFTDropCollection.sol, _burn
    MarketSharedCore.sol, _getSellerOf
    NFTCollection.sol, _burn
    OZAccessControlUpgradeable.sol, _revokeRole
    SequentialMintCollection.sol, _burn
    ArrayLibrary.sol, capLength
    BasicERC721.sol, _safeTransfer

Change if -> revert pattern to require

Change if -> revert pattern to 'require' to save gas and improve code quality, if (some_condition) { revert(revert_message) }

to: require(!some_condition, revert_message)

In the following locations:

Code instance:

    BasicERC721.sol, 303

createNFTDropCollection gas reporter results:
  using > 0 (current):
    - 319246  ·     319578  ·      319361
  using != 0 (recommendation):
    -  319252  ·     319584  ·      319367
  impact: +6 gas