Yield Witch v2 contest - kyteg's results

Fixed-rate borrowing and lending on Ethereum

General Information

Platform: Code4rena

Start Date: 14/07/2022

Pot Size: $25,000 USDC

Total HM: 2

Participants: 63

Period: 3 days

Judge: PierrickGT

Total Solo HM: 1

Id: 147

League: ETH

Yield

Findings Distribution

Researcher Performance

Rank: 20/63

Findings: 2

Award: $57.91

🌟 Selected for report: 0

🚀 Solo Findings: 0

External Links

Code4rena Contest Page Github Contest Repository Github Findings Repository Yield

Findings Information

🌟 Selected for report: hickuphh3

Also found by: 0x29A, 0x52, 0xNazgul, Chom, Deivitto, ElKu, Funen, IllIllI, Meera, ReyAdmirado, SooYa, TomJ, Trumpero, Waze, __141345__, ak1, asutorufos, c3phas, cRat1st0s, csanuragjain, delfin454000, exd0tpy, fatherOfBlocks, hake, hansfriese, horsefacts, hyh, karanctf, kenzo, kyteg, ladboy233, pashov, peritoflores, rajatbeladiya, rbserver, reassor, rokinot, simon135, wastewa

Awards

39.0585 USDC - $39.06

Labels

bug

QA (Quality Assurance)

External Links

Link to GitHub issue

Typos in comments

There are 7 instances of this issue:

FILE: contracts/Witch.sol

213:    /// Useful as a method so it can be overriden by specialised witches that may need to do extra accounting or notify 3rd parties

"overriden" should be "overridden". https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L213

FILE: contracts/Witch.sol

220:     /// @dev Calculates the auction initial values, the 2 non-trivial values are how much art must be repayed

"repayed" should be "repaid". https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L220

FILE: contracts/Witch.sol

267:     /// Useful as a method so it can be overriden by specialised witches that may need to do extra accounting or notify 3rd parties

"overriden" should be "overridden". https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L267

FILE: contracts/Witch.sol

385:     /// @dev transfers funds from the ilkJoin to the liquidator (and potentially the auctioneer if they're differente people)

"differente" should be "different" https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L385

FILE: contracts/Witch.sol

462:     /// Useful as a method so it can be overriden by specialised witches that may need to do extra accounting or notify 3rd parties

"overriden" should be "overridden". https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L267

FILE: contracts/Witch.sol

497:      /  12   \  First lets check how much time `t` is left on the auction

"lets" should be "let's" https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L497

FILE: contracts/Witch.sol

520:     /// @dev quoutes hoy much ink a liquidator is expected to get if it repays an `artIn` amount

"quoutes hoy" should be "quotes how" https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L520

#0 - alcueca
2022-07-22T14:16:43Z

Thanks

Findings Information

🌟 Selected for report: IllIllI

Also found by: 0x1f8b, 0x29A, 0xKitsune, 0xNazgul, Aymen0909, Chom, Deivitto, ElKu, JC, JohnSmith, Kaiziron, Limbooo, MadWookie, Meera, ReyAdmirado, Rohan16, Sm4rty, SooYa, TomJ, Trumpero, Waze, __141345__, ajtra, ak1, antonttc, bulej93, c3phas, cRat1st0s, csanuragjain, defsec, durianSausage, fatherOfBlocks, gogo, hake, hickuphh3, ignacio, joestakey, karanctf, kyteg, m_Rassska, pashov, rajatbeladiya, rbserver, robee, rokinot, samruna, sashik_eth, simon135, tofunmi

Awards

18.8453 USDC - $18.85

Labels

bug

G (Gas Optimization)

External Links

Link to GitHub issue

Summary

Issue	Instances
Use custom errors instead of `revert()`/`require()` to save gas	17
`internal` functions that are only called once can be inlined to save gas	1
Use `!= 0` instead of `> 0` for a `uint`	6

Gas Optimisations

Use custom errors instead of `revert()`/`require()` to save gas

Custom errors are available from solidity version 0.8.4. The instances below match or exceed that version. Saves about 200 gas per instance when the contract reverts.

There are 17 instances of this issue:

FILE: contracts/Witch.sol

84:     require(param == "ladle", "Unrecognized");

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L84

FILE: contracts/Witch.sol

102:   require(initialOffer <= 1e18, "InitialOffer above 100%");

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L102

FILE: contracts/Witch.sol

103:   require(proportion <= 1e18, "Proportion above 100%");

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L103

FILE: contracts/Witch.sol

104     require(
105         initialOffer == 0 || initialOffer >= 0.01e18,
106         "InitialOffer below 1%"
107:    );

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L104-L107

FILE: contracts/Witch.sol

108:    require(proportion >= 0.01e18, "Proportion below 1%");

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L108

FILE: contracts/Witch.sol

189:    require(cauldron.level(vaultId) < 0, "Not undercollateralized");

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L189

FILE: contracts/Witch.sol

200: 	require(limits_.sum <= limits_.max, "Collateral limit reached");

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L200

FILE: contracts/Witch.sol

255:    require(auction_.start > 0, "Vault not under auction");

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L255

FILE: contracts/Witch.sol

256:    require(cauldron.level(vaultId) >= 0, "Undercollateralized");;

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L256

FILE: contracts/Witch.sol

300:    require(auction_.start > 0, "Vault not under auction");

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L300

FILE: contracts/Witch.sol

313:    require(liquidatorCut >= minInkOut, "Not enough bought");

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L313

FILE: contracts/Witch.sol

328:    require(baseJoin != IJoin(address(0)), "Join not found");

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L328

FILE: contracts/Witch.sol

358:    require(auction_.start > 0, "Vault not under auction");

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L358

FILE: contracts/Witch.sol

365:    require(liquidatorCut >= minInkOut, "Not enough bought");

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L365

FILE: contracts/Witch.sol

395:     require(ilkJoin != IJoin(address(0)), "Join not found");

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L395

FILE: contracts/Witch.sol

416:    require(auction_.start > 0, "Vault not under auction");

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L416

FILE: contracts/Witch.sol

437   	require(
438	    	auction_.art - artIn >= debt.min * (10**debt.dec),
439		    "Leaves dust"
440:	);

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L437-L440

`internal` functions that are only called once can be inlined to save gas

Depending on the function contents, this will save 20~40 gas by omiting two JUMP operations and stack operations needed for the function call.

There is 1 instance of this issue:

FILE: contracts/Witch.sol

214:   function _auctionStarted(bytes12 vaultId) internal virtual {

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L214

Use `!= 0` instead of `> 0` for a `uint`

uint can never be below 0, so != 0 and > 0 are equivalent.

See: https://github.com/byterocket/c4-common-issues/blob/main/0-Gas-Optimizations.md/#g003---use--0-instead-of--0-for-unsigned-integer-comparison

There are 6 instances of this issue:

FILE: contracts/Witch.sol

255:    require(auction_.start > 0, "Vault not under auction");

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L255

FILE: contracts/Witch.sol

300:    require(auction_.start > 0, "Vault not under auction");

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L300

FILE: contracts/Witch.sol

358:    require(auction_.start > 0, "Vault not under auction");

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L358

FILE: contracts/Witch.sol

393:     if (liquidatorCut > 0) {

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L393

FILE: contracts/Witch.sol

398:     if (auctioneerCut > 0) {

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L398

FILE: contracts/Witch.sol

416:     require(auction_.start > 0, "Vault not under auction");

https://github.com/code-423n4/2022-07-yield/blob/main/contracts/Witch.sol#L416

Yield Witch v2 contest - kyteg's results

Fixed-rate borrowing and lending on Ethereum

General Information

Findings Distribution

Researcher Performance

External Links

[Q-23] QA Report - $39.06

Findings Information

Awards

Labels

External Links

Typos in comments

#0 - alcueca2022-07-22T14:16:43Z

[G-24] Gas Report - $18.85

Findings Information

Awards

Labels

External Links

Summary

Gas Optimisations

Use custom errors instead of revert()/require() to save gas

internal functions that are only called once can be inlined to save gas

Use != 0 instead of > 0 for a uint

#0 - alcueca
2022-07-22T14:16:43Z

Use custom errors instead of `revert()`/`require()` to save gas

`internal` functions that are only called once can be inlined to save gas

Use `!= 0` instead of `> 0` for a `uint`