veToken Finance contest - robee's results

Loss Of Precision

This issue is about arithmetic computation that could have been done more percise. The following are places in the codebase in which you multiplied after the divisions. Doing the multiplications at start lead to more accurate calculations. This is a list of places in the code that this appears (Solidity file, line number, actual line):

Code instances:

    VE3DLocker.sol, 376, uint256 currentEpoch = block.timestamp.div(rewardsDuration).mul(rewardsDuration);
    VE3DLocker.sol, 121, uint256 currentEpoch = block.timestamp.div(rewardsDuration).mul(rewardsDuration); 
    VE3DLocker.sol, 485, uint256 nextEpoch = block.timestamp.div(rewardsDuration).mul(rewardsDuration).add( rewardsDuration );
    VE3DLocker.sol, 535, uint256 lockEpoch = block.timestamp.div(rewardsDuration).mul(rewardsDuration); 
    VE3DLocker.sol, 422, _time = _time.div(rewardsDuration).mul(rewardsDuration); 

Does not validate the input fee parameter

Some fee parameters of functions are not checked for invalid values. Validate the parameters:

Code instances:

    Booster.setFees (_stakerLockIncentiveFee)
    Booster.setFees (_lockFees)
    Booster.setFeeManager (_feeM)
    Booster.setFees (_callerFees)
    VeAssetDepositor.setFeeManager (_feeManager)

safeApprove of openZeppelin is deprecated

You use safeApprove of openZeppelin although it's deprecated. (see https://github.com/OpenZeppelin/openzeppelin-contracts/blob/566a774222707e424896c0c390a84dc3c13bdcb2/contracts/token/ERC20/utils/SafeERC20.sol#L38) You should change it to increase/decrease Allowance as OpenZeppilin says.

Code instances:

    Deprecated safeApprove in VE3DLocker.sol line 214: IERC20(rewardData[_rewardsToken].ve3Token).safeApprove(
    Deprecated safeApprove in VoterProxy.sol line 160: IERC20(veAsset).safeApprove(escrow, _value);
    Deprecated safeApprove in VE3DLocker.sol line 220: IERC20(_rewardsToken).safeApprove(rewardData[_rewardsToken].veAssetDeposits, 0);
    Deprecated safeApprove in VE3DRewardPool.sol line 286: IERC20(_rewardToken).safeApprove(rewardTokenInfo[_rewardToken].veAssetDeposits, 0);
    Deprecated safeApprove in VeAssetDepositor.sol line 161: IERC20(minter).safeApprove(_stakeAddress, _amount);

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: VE3DLocker.sol, In line 154 with Empty Require message.
    Solidity file: VE3DLocker.sol, In line 180 with Empty Require message.
    Solidity file: VE3DLocker.sol, In line 155 with Empty Require message.

Require with not comprehensive message

The following requires has a non comprehensive messages. This is very important to add a comprehensive message for any require. Such that the user has enough information to know the reason of failure:

Code instances:

    Solidity file: RewardFactory.sol, In line 80 with Require message: !auth
    Solidity file: Booster.sol, In line 124 with Require message: !auth
    Solidity file: VoterProxy.sol, In line 167 with Require message: !auth
    Solidity file: Booster.sol, In line 468 with Require message: !auth
    Solidity file: Booster.sol, In line 261 with Require message: !add

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:

    VE3DLocker.sol.approveRewardDistributor _rewardsToken
    BaseRewardPool.sol.stakeFor _for
    PoolManager.sol.addPool _lptoken
    VeTokenMinter.sol.withdraw _destination
    SmartWalletWhitelist.sol.approveWallet _wallet

Treasury may be address(0)

Make sure the treasury is not address(0).
    
    

Code instance:

    Booster.sol.setTreasury _treasury

Solidity compiler versions mismatch

The project is compiled with different versions of solidity, which is not recommended because it can lead to undefined behaviors.

Code instance:

Use safe math for solidity version <8

You should use safe math for solidity version <8 since there is no default over/under flow check it suchversions of solidity.

Code instances:

    The contract Babylonian.sol doesn't use safe math and is of solidity version < 8
    The contract FullMath.sol doesn't use safe math and is of solidity version < 8
    The contract BitMath.sol doesn't use safe math and is of solidity version < 8
    The contract FixedPoint.sol doesn't use safe math and is of solidity version < 8
    The contract Migrations.sol doesn't use safe math and is of solidity version < 8

Not verified owner

    owner param should be validated to make sure the owner address is not address(0).
    Otherwise if not given the right input all only owner accessible functions will be unaccessible.
    
    

Code instances:

    Booster.sol.setOwner _owner
    VoterProxy.sol.setOwner _owner

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:

    VE3DLocker.sol, balanceAtEpochOf
    VE3DLocker.sol, findEpochId
    VE3DLocker.sol, totalSupplyAtEpoch
    VE3DLocker.sol, lockedBalances
    VE3DLocker.sol, totalSupply

Two Steps Verification before Transferring Ownership

The following contracts have a function that allows them an admin to change it to a different address. If the admin accidentally uses an invalid address for which they do not have the private key, then the system gets locked. It is important to have two steps admin change where the first is announcing a pending new admin and the new address should then claim its ownership. A similar issue was reported in a previous contest and was assigned a severity of medium: code-423n4/2021-06-realitycards-findings#105

Code instances:

    VoterProxy.sol
    VeAssetDepositor.sol
    IPools.sol
    Booster.sol

Missing non reentrancy modifier

The following functions are missing reentrancy modifier although some other pulbic/external functions does use reentrancy modifer. Even though I did not find a way to exploit it, it seems like those functions should have the nonReentrant modifier as the other functions have it as well..

Code instances:

    VE3DLocker.sol, recoverERC20 is missing a reentrancy modifier
    VE3DLocker.sol, setApprovals is missing a reentrancy modifier

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 instance:

    VeTokenMinter.sol, updateveAssetWeight

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:

    VoterProxy.sol: function execute parameter _data isn't used. (execute is external)
    VoterProxy.sol: function execute parameter _value isn't used. (execute is external)
    VoterProxy.sol: function execute parameter _to isn't used. (execute 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-423n4/2022-05-vetoken/tree/main/contracts/ExtraRewardStashV2.sol#L96
    https://github.com/code-423n4/2022-05-vetoken/tree/main/contracts/VE3DLocker.sol#L683
    https://github.com/code-423n4/2022-05-vetoken/tree/main/contracts/VeTokenMinter.sol#L78
    https://github.com/code-423n4/2022-05-vetoken/tree/main/contracts/VeTokenMinter.sol#L72
    https://github.com/code-423n4/2022-05-vetoken/tree/main/contracts/BaseRewardPool.sol#L208

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 instance:

    VeTokenMinter.sol, updateveAssetWeight

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:

    VoterProxy.sol: function execute parameter _data isn't used. (execute is external)
    VoterProxy.sol: function execute parameter _value isn't used. (execute is external)
    VoterProxy.sol: function execute parameter _to isn't used. (execute is external)

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-423n4/2022-05-vetoken/tree/main/contracts/Booster.sol#L243
    https://github.com/code-423n4/2022-05-vetoken/tree/main/contracts/RewardFactory.sol#L79
    https://github.com/code-423n4/2022-05-vetoken/tree/main/contracts/token/VE3Token.sol#L21
    https://github.com/code-423n4/2022-05-vetoken/tree/main/contracts/Booster.sol#L141
    https://github.com/code-423n4/2022-05-vetoken/tree/main/contracts/VE3DLocker.sol#L206

Unnecessary equals boolean

Boolean variables can be checked within conditionals directly without the use of equality operators to true/false.

Code instances:

    RewardFactory.sol, 40: require(rewardAccess[msg.sender] == true, "!auth");
    ExtraRewardStashV1.sol, 152: if (token == address(0)) return true;
    RewardFactory.sol, 103: require(operators.contains(_msgSender()) || rewardAccess[_msgSender()] == true, "!auth");
    VoterProxy.sol, 96: if (protectedTokens[_gauge] == false) {
    Booster.sol, 498: require(pool.shutdown == false, "pool is closed");

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:

    _symbol in VE3DLocker.sol
    veToken in VeTokenMinter.sol
    _name in VE3DLocker.sol
    rewardFactory in StashFactory.sol
    totalCliffs in VeTokenMinter.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:

    ExtraRewardStashV1.sol, maxRewards
    ExtraRewardStashV3.sol, WEEK

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 instances:

    VE3DLocker.sol, _checkpointEpoch, nextEpochDate
    VE3DLocker.sol, constructor, currentEpoch

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:

    BaseRewardPool.sol, extraRewards, 218
    Booster.sol, poolInfo, 329
    VE3DLocker.sol, userRewards, 286
    VE3DLocker.sol, locks, 457
    VE3DLocker.sol, rewardTokens, 720

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:

    change to prefix increment and unchecked: VE3DRewardPool.sol, i, 257
    change to prefix increment and unchecked: VE3DLocker.sol, i, 720
    change to prefix increment and unchecked: Booster.sol, i, 329
    change to prefix increment and unchecked: ExtraRewardStashV2.sol, i, 213
    change to prefix increment and unchecked: VE3DLocker.sol, i, 457

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:

    ExtraRewardStashV2.sol, 137
    RewardFactory.sol, 49
    ExtraRewardStashV3.sol, 84
    BaseRewardPool.sol, 199
    VE3DRewardPool.sol, 148

Unnecessary default assignment

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

Code instances:

    BaseRewardPool.sol (L#70) : uint256 public queuedRewards = 0;
    VeAssetDepositor.sol (L#28) : uint256 public incentiveVeAsset = 0;
    VirtualBalanceRewardPool.sol (L#74) : uint256 public periodFinish = 0;
    BaseRewardPool.sol (L#71) : uint256 public currentRewards = 0;
    VirtualBalanceRewardPool.sol (L#78) : uint256 public queuedRewards = 0;

Rearrange state variables

You can change the order of the storage variables to decrease memory uses.

Code instances:

In VoterProxy.sol,rearranging the storage fields can optimize to: 9 slots from: 10 slots. The new order of types (you choose the actual variables): 1. string 2. IVoteEscrow.EscrowModle 3. address 4. bytes4 5. address 6. address 7. address 8. address 9. address 10. address

In VE3DLocker.sol,rearranging the storage fields can optimize to: 11 slots from: 12 slots. The new order of types (you choose the actual variables): 1. IERC20 2. EnumerableSet.AddressSet 3. uint256 4. uint256 5. uint256 6. uint256 7. uint256 8. uint256 9. string 10. string 11. uint8 12. bool

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: BitMath.sol, In line 45, Require message length to shorten: 34, The message: BitMath::leastSignificantBit: zero
    Solidity file: FixedPoint.sol, In line 85, Require message length to shorten: 33, The message: FixedPoint::muluq: upper overflow
    Solidity file: FixedPoint.sol, In line 105, Require message length to shorten: 35, The message: FixedPoint::divuq: division by zero
    Solidity file: BitMath.sol, In line 8, Require message length to shorten: 33, The message: BitMath::mostSignificantBit: zero
    Solidity file: FixedPoint.sol, In line 131, Require message length to shorten: 38, The message: FixedPoint::fraction: division by zero

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:

    BaseRewardPool.sol, 196: change '_amount > 0' to '_amount != 0'
    VE3DLocker.sol, 649: change '_checkDelay > 0' to '_checkDelay != 0'
    VE3DLocker.sol, 626: change '_checkDelay > 0' to '_checkDelay != 0'
    Booster.sol, 590: change 'stakerLockFeesIncentive > 0' to 'stakerLockFeesIncentive != 0'
    BitMath.sol, 8: change 'x > 0' to 'x != 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:

    VeAssetDepositor.sol (L#73) - uint256 unlockAt = block.timestamp + maxTime;
    ExtraRewardStashV1.sol (L#106) - if (block.timestamp > tokenInfo.lastActiveTime + WEEK) { 
    VeAssetDepositor.sol (L#102) - uint256 unlockAt = block.timestamp + maxTime;
    ExtraRewardStashV2.sol (L#187) - if (block.timestamp <= t.lastActiveTime + WEEK) {
    ExtraRewardStashV2.sol (L#101) - if (block.timestamp > tokenInfo[i].lastActiveTime + WEEK) { 

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

    FixedPoint.sol, decode, { return uint112(self._x >> RESOLUTION); }
    FixedPoint.sol, decode144, { return uint144(self._x >> RESOLUTION); }
    FixedPoint.sol, encode144, { return uq144x112(uint256(x) << RESOLUTION); }
    FixedPoint.sol, encode, { return uq112x112(uint224(x) << RESOLUTION); }
    VE3DLocker.sol, _lastTimeRewardApplicable, { return Math.min(block.timestamp, _finishTime); }

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:

    VE3DLocker.sol, _notifyReward
    ExtraRewardStashV3.sol, checkForNewRewardTokens
    VoterProxy.sol, _withdrawSome
    Booster.sol, _earmarkRewards
    ExtraRewardStashV1.sol, setToken

Upgrade pragma to at least 0.8.4

Using newer compiler versions and the optimizer gives gas optimizations and additional safety checks are available for free.

The advantages of versions 0.8.* over <0.8.0 are:

    1. Safemath by default from 0.8.0 (can be more gas efficient than library based safemath.)
    2. Low level inliner : from 0.8.2, leads to cheaper runtime gas. Especially relevant when the contract has small functions. For example, OpenZeppelin libraries typically have a lot of small helper functions and if they are not inlined, they cost an additional 20 to 40 gas because of 2 extra jump instructions and additional stack operations needed for function calls.
    3. Optimizer improvements in packed structs: Before 0.8.3, storing packed structs, in some cases used an additional storage read operation. After EIP-2929, if the slot was already cold, this means unnecessary stack operations and extra deploy time costs. However, if the slot was already warm, this means additional cost of 100 gas alongside the same unnecessary stack operations and extra deploy time costs.
    4. Custom errors from 0.8.4, leads to cheaper deploy time cost and run time cost. Note: the run time cost is only relevant when the revert condition is met. In short, replace revert strings by custom errors.

Code instances:

    FullMath.sol
    Babylonian.sol
    FixedPoint.sol
    BitMath.sol
    Migrations.sol

Do not cache msg.sender

We recommend not to cache msg.sender since calling it is 2 gas while reading a variable is more.

Code instances:

    https://github.com/code-423n4/2022-05-vetoken/tree/main/contracts/VoterProxy.sol#L52
    https://github.com/code-423n4/2022-05-vetoken/tree/main/contracts/VeAssetDepositor.sol#L48
    https://github.com/code-423n4/2022-05-vetoken/tree/main/contracts/token/VE3Token.sol#L19
    https://github.com/code-423n4/2022-05-vetoken/tree/main/contracts/token/VeToken.sol#L16
    https://github.com/code-423n4/2022-05-vetoken/tree/main/contracts/Booster.sol#L112