OpenLeverage contest - mics's results

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Vulnerability details

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. This appears in the following locations in the code base:

    Deprecated safeApprove in OpenLevV1.sol line 275: marketVars.sellToken.safeApprove(address(addressConfig.dexAggregator), maxSell); 
    Deprecated safeApprove in XOLE.sol line 98: (IERC20(fromToken)).safeApprove(address(dexAgg), amount); 
    Deprecated safeApprove in OpenLevV1Lib.sol line 54: IERC20(token1).safeApprove(address(pool1), uint256(- 1)); 
    Deprecated safeApprove in OpenLevV1Lib.sol line 53: IERC20(token0).safeApprove(address(pool0), uint256(- 1)); 
    Deprecated safeApprove in XOLE.sol line 97: (IERC20(fromToken)).safeApprove(address(dexAgg), 0); 
    Deprecated safeApprove in OpenLevV1.sol line 455: IERC20(sellToken).safeApprove(address(dexAggregator), maxSellAmount); 
    Deprecated safeApprove in OpenLevV1.sol line 447: IERC20(sellToken).safeApprove(address(dexAggregator), sellAmount); 

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Vulnerability details

From solidity docs: Properly functioning code should never reach a failing assert statement; if this happens there is a bug in your contract which you should fix. With assert the user pays the gas and with require it doesn't. The ETH network gas isn't cheap and users can see it as a scam. You have reachable asserts in the following locations (which should be replaced by require / are mistakenly left from development phase):

    FarmingPools.sol : reachable assert in line 77
    XOLE.sol : reachable assert in line 303

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Vulnerability details

To improve algorithm precision instead using division in comparison use multiplication in the following scenario: Instead a < b / c use a * c < b.

In all of the big and trusted contracts this rule is maintained (for example look at AAVE codebase).

    OpenLevV1.sol, 125, require(borrow == 0 || deposit.mul(10000).div(tv.borrowValue) > vars.marginLimit, "MAM");
    OpenLevV1Lib.sol, 166, uint hAvg = marketValue >= borrowed ? marketValue.sub(borrowed).mul(ratioVars.multiplier).div(borrowed) : 0;
    OpenLevV1.sol, 219, require(repayed >= closeTradeVars.borrowed.mul(closeTradeVars.closeRatio).div(1e18), "IRP"); 
    OpenLevV1Lib.sol, 164, uint cAvg = marketValue >= borrowed ? marketValue.sub(borrowed).mul(ratioVars.multiplier).div(borrowed) : 0;
    OpenLevV1Lib.sol, 276, share = totalShare > 0 && reserve > 0 ? totalShare.mul(amount) / reserve : amount;
    OpenLevV1Lib.sol, 162, uint current = marketValue >= borrowed ? marketValue.sub(borrowed).mul(ratioVars.multiplier).div(borrowed) : 0;
    LPool.sol, 892, require(vars.actualRepayAmount.mul(1e18).div(vars.accountBorrows) <= 105e16, 'repay more than 5%');

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Vulnerability details

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).

    OpenLevV1Lib.sol, updatePrice
    OpenLevV1.sol, updatePrice
    BscDexAggregatorV1.sol, updateV3Observation
    ControllerV1.sol, updatePriceAllowed
    EthDexAggregatorV1.sol, updateV3Observation

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Vulnerability details

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:

EthDexAggregatorV1.sol, i, 48 FarmingPools.sol, i, 126 FarmingPools.sol, i, 132 GovernorAlpha.sol, i, 228 OLETokenLock.sol, i, 33 ControllerV1.sol, i, 303 Airdrop.sol, i, 64 UniV3Dex.sol, i, 75 GovernorAlpha.sol, i, 202 FarmingPools.sol, i, 164 GovernorAlpha.sol, i, 307 BscDexAggregatorV1.sol, i, 46 ControllerV1.sol, i, 375 GovernorAlpha.sol, i, 280 OpenLevV1Lib.sol, i, 260 UniV2Dex.sol, i, 59 XOLE.sol, i, 362 OpenLevV1.sol, i, 52

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Vulnerability details

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

    oleToken in FarmingPools.sol
    symbol in OLEToken.sol
    xole in GovernorAlpha.sol
    timelock in GovernorAlpha.sol
    developer in Adminable.sol
    name in OLEToken.sol

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Vulnerability details

Use bytes32 instead of string to save gas whenever possible. String is a dynamic data structure and therefore is more gas consuming then bytes32. You could use bytes32 instead of string in the following places: List format: <solidity file> <line number> <actual code line>

    GovernorAlpha.sol, 13, string public constant name = "Open Leverage Governor Alpha"; 

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Vulnerability details

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++) { ... }

These functions use not using prefix increments (++x) or not using the unchecked keyword:

    OpenLevV1Lib.sol, dexs, 260
    GovernorAlpha.sol, targets.proposal, 228
    ControllerV1.sol, lpools, 303
    FarmingPools.sol, stakeTokens, 132
    OLETokenLock.sol, beneficiaries, 33
    FarmingPools.sol, stakeTokens, 126
    GovernorAlpha.sol, support, 307
    UniV3Dex.sol, path, 75
    OpenLevV1.sol, _supportDexs, 52
    UniV2Dex.sol, tokens, 59
    GovernorAlpha.sol, targets.proposal, 280
    XOLE.sol, nonce, 362
    ControllerV1.sol, marketIds, 375
    BscDexAggregatorV1.sol, dexName, 46
    FarmingPools.sol, stakeTokens, 164
    GovernorAlpha.sol, targets.proposal, 202
    EthDexAggregatorV1.sol, dexName, 48

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Vulnerability details

In Adminable.sol line 37 you can short the require message from "only pendingAdmin can accept admin" to "you're not a pendingAdmin" and then it will be in 1 slot and save gas.

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Vulnerability details

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.

XOLEDelegator.sol Timelock.sol ControllerV1.sol

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Vulnerability details

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

    OpenLevV1.sol, 454: change 'buyAmount > 0' to 'buyAmount != 0'
    OpenLevV1Lib.sol, 112: change 'marginLimit > 0' to 'marginLimit != 0'
    OpenLevV1.sol, 424: change 'balance > 0' to 'balance != 0'
    UniV2Dex.sol, 207: change 'reserveIn > 0' to 'reserveIn != 0'
    ControllerV1.sol, 342: change 'supplyAmount > 0' to 'supplyAmount != 0'
    UniV3Dex.sol, 165: change 'amount0Delta > 0' to 'amount0Delta != 0'
    OpenLevV1Lib.sol, 276: change 'totalShare > 0' to 'totalShare != 0'
    XOLE.sol, 266: change '_value > 0' to '_value != 0'
    ControllerV1.sol, 363: change 'borrowAmount > 0' to 'borrowAmount != 0'

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Vulnerability details

Use calldata instead of memory for function parameters In some cases, having function arguments in calldata instead of memory is more optimal.

Consider the following generic example:

    contract C {
        function add(uint[] memory arr) external returns (uint sum) {
            uint length = arr.length;
            for (uint i = 0; i < arr.length; i++) {
                sum += arr[i];
            }
        }
    }

In the above example, the dynamic array arr has the storage location
memory. When the function gets called externally, the array values are
kept in calldata and copied to memory during ABI decoding (using the
opcode calldataload and mstore). And during the for loop, arr[i]
accesses the value in memory using a mload. However, for the above
example this is inefficient. Consider the following snippet instead:

    contract C {
        function add(uint[] calldata arr) external returns (uint sum) {
            uint length = arr.length;
            for (uint i = 0; i < arr.length; i++) {
                sum += arr[i];
            }
        }
    }
In the above snippet, instead of going via memory, the value is directly
read from calldata using calldataload. That is, there are no
intermediate memory operations that carries this value.

Gas savings: In the former example, the ABI decoding begins with
copying value from calldata to memory in a for loop. Each iteration
would cost at least 60 gas. In the latter example, this can be
completely avoided. This will also reduce the number of instructions and
therefore reduces the deploy time cost of the contract.

In short, use calldata instead of memory if the function argument
is only read.

Note that in older Solidity versions, changing some function arguments
from memory to calldata may cause "unimplemented feature error".
This can be avoided by using a newer (0.8.*) Solidity compiler.

(non-exhaustive) List of Examples:


    DelegatorInterface.delegateToViewImplementation (data)
    GovernorAlpha.propose (description)
    ControllerV1.initialize (_oleWethDexData)
    OpenLevV1.marginRatio (dexData)
    BscDexAggregatorV1.updateV3Observation (data)

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Vulnerability details

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. see:

    Adminable.sol: pendingAdmin is read twice in acceptAdmin

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Vulnerability details

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

    UniV3Dex.sol, uniV3GetPriceCAvgPriceHAvgPrice
    UniV2Dex.sol, uniV2GetPriceCAvgPriceHAvgPrice
    UniV3Dex.sol, uniV3Buy
    UniV2Dex.sol, uniV2CalSellAmount
    UniV3Dex.sol, uniV3GetAvgPrice
    OpenLevV1Lib.sol, amountToShare
    OpenLevV1Lib.sol, shareToAmount
    UniV2Dex.sol, uniV2GetAvgPrice
    UniV2Dex.sol, uniV2UpdatePriceOracle
    UniV3Dex.sol, initializeUniV3
    UniV3Dex.sol, uniV3SellMul
    UniV3Dex.sol, increaseV3Observation
    UniV2Dex.sol, uniV2SellMul
    UniV2Dex.sol, uniV2CalBuyAmount
    UniV2Dex.sol, uniV2GetPrice
    UniV2Dex.sol, uniV2Buy

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Vulnerability details

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

    ControllerV1.sol, 156: if (marketExtraDistribution[marketId] == false) {
    ControllerV1.sol, 121: if (marketExtraDistribution[marketId] == false) {
    

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Vulnerability details

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 redundent second array boundaries check:

    Airdrop.sol, variable name: _balances times: 2 at: claims
    UniV2Dex.sol, variable name: tokens times: 2 at: uniV2SellMul
    OLETokenLock.sol, variable name: startTimes times: 2 at: constructor

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Vulnerability details

The following functions could skip other steps if the amount is 0. (A similar issue: https://github.com/code-423n4/2021-10-badgerdao-findings/issues/82)

    ControllerV1.sol, redeemAllowed
    OLEToken.sol, mint
    Airdrop.sol, newTranche
    LPool.sol, approve
    OLETokenLock.sol, constructor
    XOLE.sol, _mint
    LPool.sol, mintTo

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Vulnerability details

Some of your contract inherent contracts but aren't use them at all. We recommend not to inherent those contracts.

    ControllerV1.sol; the inherited contracts DelegateInterface not used
    LPool.sol; the inherited contracts DelegateInterface, LPoolInterface not used
    EthDexAggregatorV1.sol; the inherited contracts DelegateInterface not used
    BscDexAggregatorV1.sol; the inherited contracts DelegateInterface, UniV2ClassDex not used
    OpenLevV1.sol; the inherited contracts DelegateInterface not used