Platform: Code4rena
Start Date: 12/08/2022
Pot Size: $50,000 USDC
Total HM: 15
Participants: 120
Period: 5 days
Judge: Justin Goro
Total Solo HM: 6
Id: 153
League: ETH
Rank: 56/120
Findings: 2
Award: $67.04
🌟 Selected for report: 0
🚀 Solo Findings: 0
🌟 Selected for report: 0x1f8b
Also found by: 0x52, 0xA5DF, 0xDjango, 0xNazgul, 0xNineDec, 0xSmartContract, 0xmatt, 0xsolstars, Aymen0909, Bnke0x0, CertoraInc, Chom, CodingNameKiki, Deivitto, Dravee, ElKu, EthLedger, Funen, IllIllI, JC, Junnon, Lambda, LeoS, MiloTruck, Noah3o6, PaludoX0, ReyAdmirado, Rohan16, RoiEvenHaim, Rolezn, SaharAP, Sm4rty, SooYa, The_GUILD, TomJ, Waze, Yiko, _Adam, __141345__, a12jmx, ak1, asutorufos, auditor0517, ayeslick, ballx, beelzebufo, berndartmueller, bin2chen, brgltd, c3phas, cRat1st0s, cccz, cryptonue, cryptphi, d3e4, delfin454000, dipp, djxploit, durianSausage, dy, erictee, fatherOfBlocks, gogo, gzeon, hyh, ignacio, kyteg, ladboy233, medikko, mics, minhquanym, oyc_109, pfapostol, rbserver, reassor, ret2basic, robee, sach1r0, simon135, sryysryy, tabish, yac, yash90, zzzitron
45.8341 USDC - $45.83
-> EVENT IS MISSING INDEXED FIELDS Each event should use three indexed fields if there are three or more fields.
https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=event%20UpdateRate(uint256%20_ratePerSec%2C%20uint256%20_deltaTime%2C%20uint256%20_utilizationRate%2C%20uint256%20_newRatePerSec)%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=event%20RepayAsset(address%20indexed%20_sender%2C%20address%20indexed%20_borrower%2C%20uint256%20_amountToRepay%2C%20uint256%20_shares)%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=event%20Liquidate(,uint256%20_amountToAdjust https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=event%20LeveragedPosition(,uint256%20_amountCollateralOut
-> _SAFEMINT() SHOULD BE USED RATHER THAN _MINT() WHEREVER POSSIBLE
_mint() is discouraged in favor of _safeMint() which ensures that the recipient is either an EOA or implements IERC721Receiver
https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=_mint(address(this)%2C%20_feesShare)%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=_mint(_receiver%2C%20_shares)%3B
🌟 Selected for report: IllIllI
Also found by: 0x1f8b, 0xA5DF, 0xDjango, 0xNazgul, 0xSmartContract, 0xackermann, 0xbepresent, 0xc0ffEE, 0xkatana, 2997ms, Amithuddar, Aymen0909, Bnke0x0, Chinmay, Chom, CodingNameKiki, Deivitto, Diraco, Dravee, ElKu, EthLedger, Fitraldys, Funen, IgnacioB, JC, Junnon, Lambda, LeoS, Metatron, MiloTruck, Noah3o6, NoamYakov, PaludoX0, Randyyy, ReyAdmirado, Rohan16, Rolezn, Ruhum, SaharAP, Sm4rty, SooYa, TomJ, Tomio, Waze, Yiko, _Adam, __141345__, a12jmx, ajtra, ak1, asutorufos, ballx, brgltd, c3phas, cRat1st0s, carlitox477, chrisdior4, d3e4, delfin454000, dharma09, djxploit, durianSausage, erictee, fatherOfBlocks, find_a_bug, flyx, francoHacker, gerdusx, gogo, gzeon, hakerbaya, ignacio, jag, kyteg, ladboy233, ltyu, m_Rassska, medikko, mics, mrpathfindr, newfork01, nxrblsrpr, oyc_109, pfapostol, rbserver, reassor, ret2basic, robee, sach1r0, saian, simon135, sryysryy, zeesaw
21.2057 USDC - $21.21
-> X = X + Y IS CHEAPER THAN X += Y (same for X = X - Y IS CHEAPER THAN X -= Y)
https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPair.sol#:~:text=_totalAsset.amount%20%2D%3D%20uint128(_amountToTransfer) https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPair.sol#:~:text=_totalAsset.shares%20%2D%3D%20_shares%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=_totalBorrow.amount%20%2B%3D%20uint128(_interestEarned)%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=_totalAsset.amount%20%2B%3D%20uint128(_interestEarned)%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=_totalAsset.shares%20%2B%3D%20uint128(_feesShare)%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=_totalAsset.amount%20%2B%3D%20_amount%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=_totalAsset.shares%20%2B%3D%20_shares%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=_totalAsset.amount%20%2D%3D%20_amountToReturn%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=_totalAsset.shares%20%2D%3D%20_shares%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=_totalBorrow.amount%20%2B%3D%20_borrowAmount%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=_totalBorrow.shares%20%2B%3D%20uint128(_sharesAdded)%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=userBorrowShares%5Bmsg.sender%5D%20%2B%3D%20_sharesAdded%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=_totalBorrow.amount%20%2D%3D%20_amountToRepay%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=_totalBorrow.shares%20%2D%3D%20_shares%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=userBorrowShares%5B_borrower%5D%20%2D%3D%20_shares%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=totalAsset.amount%20%2D%3D%20_amountToAdjust%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=_totalBorrow.amount%20%2D%3D%20_amountToAdjust%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=_totalBorrow.shares%20%2D%3D%20_sharesToAdjust%3B
->STATE VARIABLES ONLY SET IN THE CONSTRUCTOR SHOULD BE DECLARED IMMUTABLE
Avoids a Gsset (20000 gas) in the constructor, and replaces each Gwarmacces (100 gas) with a PUSH32 (3 gas)
https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=IERC20%20internal%20immutable%20assetContract%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=IERC20%20public%20immutable%20collateralContract%3B
-> REQUIRE()/REVERT() STRINGS LONGER THAN 32 BYTES COST EXTRA GAS
USE CUSTOM ERRORS RATHER THAN REVERT()/REQUIRE() STRINGS TO SAVE GAS
https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairDeployer.sol#:~:text=%22FraxlendPairDeployer%3A%20create2%20failed%22)%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairDeployer.sol#:~:text=%22FraxlendPairDeployer%3A%20Pair%20name%20must%20be%20unique%22)%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairDeployer.sol#:~:text=%22FraxlendPairDeployer%3A%20_maxLTV%20is%20too%20large%22)%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairDeployer.sol#:~:text=%22FraxlendPairDeployer%3A%20Only%20whitelisted%20addresses%22 https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/LinearInterestRate.sol#:~:text=%22LinearInterestRate%3A%20_minInterest%20%3C%20MAX_INT%20%26%26%20_minInterest%20%3C%3D%20_vertexInterest%20%26%26%20_minInterest%20%3E%3D%20MIN_INT%22 https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/LinearInterestRate.sol#:~:text=%22LinearInterestRate%3A%20_maxInterest%20%3C%3D%20MAX_INT%20%26%26%20_vertexInterest%20%3C%3D%20_maxInterest%20%26%26%20_maxInterest%20%3E%20MIN_INT%22 https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/LinearInterestRate.sol#:~:text=%22LinearInterestRate%3A%20_vertexUtilization%20%3C%20MAX_VERTEX_UTIL%20%26%26%20_vertexUtilization%20%3E%200%22
->USING > 0 COSTS MORE GAS THAN != 0 WHEN USED ON A UINT IN A REQUIRE() STATEMENT
->SPLITTING REQUIRE() STATEMENTS THAT USE && SAVES GAS
https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/LinearInterestRate.sol#:~:text=)%3B-,require(,)%3B,-require( https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/LinearInterestRate.sol#:~:text=)%3B-,require(,)%3B,-require( https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/LinearInterestRate.sol#:~:text=_maxInterest%20%26%26%20_maxInterest%20%3E%20MIN_INT%22-,)%3B,)%3B,-%7D
-> ++i costs less gas compared to i++ or i += 1 (Also --i costs less gas compared to i--- or i -= 1)
https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPair.sol#:~:text=_lenders.length%3B-,i%2B%2B)%20%7B,-//%20Do%20not%20set https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPair.sol#:~:text=_borrowers.length%3B-,i%2B%2B)%20%7B,-//%20Do%20not%20set https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPair.sol#:~:text=_lenders.length%3B-,i%2B%2B)%20%7B,-//%20Do%20not%20set https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPair.sol#:~:text=_borrowers.length%3B-,i%2B%2B)%20%7B,-//%20Do%20not%20set https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairDeployer.sol#:~:text=deployedPairsByName%5B_deployedPairsArray%5Bi%5D%5D%3B-,unchecked%20%7B,%7D,-%7D https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairDeployer.sol#:~:text=%7D)%3B-,unchecked%20%7B,%7D,-%7D https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendWhitelist.sol#:~:text=_addresses.length%3B-,i%2B%2B)%20%7B,-oracleContractWhitelist%5B_addresses%5Bi https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendWhitelist.sol#:~:text=_addresses.length%3B-,i%2B%2B)%20%7B,-rateContractWhitelist%5B_addresses%5Bi https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendWhitelist.sol#:~:text=_addresses.length%3B-,i%2B%2B)%20%7B,-fraxlendDeployerWhitelist%5B_addresses%5Bi
-> USAGE OF UINTS/INTS SMALLER THAN 32 BYTES (256 BITS) INCURS OVERHEAD When using elements that are smaller than 32 bytes, your contract’s gas usage may be higher. This is because the EVM operates on 32 bytes at a time. Therefore, if the element is smaller than that, the EVM must use more operations in order to reduce the size of the element from 32 bytes to the desired size.
https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPair.sol#:~:text=uint16%20_DEFAULT_PROTOCOL_FEE%2C https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairConstants.sol#:~:text=uint16%20internal%20constant%20DEFAULT_PROTOCOL_FEE%20%3D%200%3B
->IT COSTS MORE GAS TO INITIALIZE NON-CONSTANT/NON-IMMUTABLE VARIABLES TO ZERO THAN TO LET THE DEFAULT OF ZERO BE APPLIED
If a variable is not set/initialized, it is assumed to have the default value (0, false, 0x0 etc depending on the data type). Explicitly initializing it with its default value is an anti-pattern and wastes gas.
https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPair.sol#:~:text=for%20(uint256%20i%20%3D%200%3B%20i%20%3C%20_lenders.length%3B%20i%2B%2B)%20%7B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPair.sol#:~:text=for%20(uint256%20i%20%3D%200%3B%20i%20%3C%20_borrowers.length%3B%20i%2B%2B)%20%7B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=for%20(uint256%20i%20%3D%200%3B%20i%20%3C%20_approvedBorrowers.length%3B%20%2B%2Bi)%20%7B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=for%20(uint256%20i%20%3D%200%3B%20i%20%3C%20_approvedLenders.length%3B%20%2B%2Bi)%20%7B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPair.sol#:~:text=for%20(uint256%20i%20%3D%200%3B%20i%20%3C%20_lenders.length%3B%20i%2B%2B)%20%7B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPair.sol#:~:text=for%20(uint256%20i%20%3D%200%3B%20i%20%3C%20_borrowers.length%3B%20i%2B%2B)%20%7B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairDeployer.sol#:~:text=uint256%20i%3B-,for%20(i%20%3D%200%3B%20i%20%3C%20_lengthOfArray%3B%20)%20%7B,-_addresses%5Bi%5D https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairDeployer.sol#:~:text=PairCustomStatus%5B%5D(_lengthOfArray)%3B-,for%20(i%20%3D%200%3B%20i%20%3C%20_lengthOfArray%3B%20)%20%7B,-_pairCustomStatuses%5Bi%5D https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairDeployer.sol#:~:text=for%20(uint256%20i%20%3D%200%3B%20i%20%3C%20_lengthOfArray%3B%20)%20%7B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendWhitelist.sol#:~:text=)%20external%20onlyOwner%20%7B-,for%20(uint256%20i%20%3D%200%3B%20i%20%3C%20_addresses.length%3B%20i%2B%2B)%20%7B,-oracleContractWhitelist%5B_addresses%5Bi https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendWhitelist.sol#:~:text=)%20external%20onlyOwner%20%7B-,for%20(uint256%20i%20%3D%200%3B%20i%20%3C%20_addresses.length%3B%20i%2B%2B)%20%7B,-rateContractWhitelist%5B_addresses%5Bi https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendWhitelist.sol#:~:text=)%20external%20onlyOwner%20%7B-,for%20(uint256%20i%20%3D%200%3B%20i%20%3C%20_addresses.length%3B%20i%2B%2B)%20%7B,-fraxlendDeployerWhitelist%5B_addresses%5Bi
->USING BOOLS FOR STORAGE INCURS OVERHEAD
https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=mapping(address%20%3D%3E%20bool)%20public%20approvedBorrowers%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairCore.sol#:~:text=mapping(address%20%3D%3E%20bool)%20public%20approvedLenders%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendPairDeployer.sol#:~:text=mapping(address%20%3D%3E%20bool)%20public%20deployedPairCustomStatusByAddress%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendWhitelist.sol#:~:text=mapping(address%20%3D%3E%20bool)%20public%20oracleContractWhitelist%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendWhitelist.sol#:~:text=mapping(address%20%3D%3E%20bool)%20public%20rateContractWhitelist%3B https://github.com/code-423n4/2022-08-frax/blob/main/src/contracts/FraxlendWhitelist.sol#:~:text=mapping(address%20%3D%3E%20bool)%20public%20fraxlendDeployerWhitelist%3B