Amun contest - Dravee's results

Handle

Dravee

Vulnerability details

Impact

Increased gas cost

Proof of Concept

(As seen on this contest: https://github.com/code-423n4/2021-10-slingshot-findings/issues/63) Reading array length at each iteration of the loop takes 6 gas (3 for mload and 3 to place memory_offset) in the stack.

Caching the array length in the stack saves around 3 gas per iteration.

Instances include:

• RebalanceManager.sol#rebalance() https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/callManagers/RebalanceManager.sol#L218 https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/callManagers/RebalanceManager.sol#L234
• RebalanceManagerV2.sol#rebalance() https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/callManagers/RebalanceManagerV2.sol#L155
• RebalanceManagerV3.sol#rebalance() https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/callManagers/RebalanceManagerV3.sol#L166 https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/callManagers/RebalanceManagerV3.sol#L171
• BasketFacet.sol#removeToken,BasketFacet.sol#joinPool,BasketFacet.sol#exitPool,BasketFacet.sol#getTokens,BasketFacet.sol#calcTokensForAmount,BasketFacet.sol#calcTokensForAmountExit https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/facets/Basket/BasketFacet.sol#L50 https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/facets/Basket/BasketFacet.sol#L160 https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/facets/Basket/BasketFacet.sol#L202 https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/facets/Basket/BasketFacet.sol#L321 https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/facets/Basket/BasketFacet.sol#L348 https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/facets/Basket/BasketFacet.sol#L381
• CallFacet.sol#call,CallFacet.sol#removeCaller,CallFacet.sol#callNoValue https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/facets/Call/CallFacet.sol#L55 https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/facets/Call/CallFacet.sol#L82 https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/facets/Call/CallFacet.sol#L95
• SingleNativeTokenExit.sol#exitEth https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/singleJoinExit/SingleNativeTokenExit.sol#L69
• SingleNativeTokenExitV2.sol#_exit https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/singleJoinExit/SingleNativeTokenExitV2.sol#L74 https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/singleJoinExit/SingleNativeTokenExitV2.sol#L76
• SingleTokenJoin.sol#_joinTokenSingle https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/singleJoinExit/SingleTokenJoin.sol#L108
• SingleTokenJoinV2.sol#_joinTokenSingle https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/singleJoinExit/SingleTokenJoinV2.sol#L86 https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/singleJoinExit/SingleTokenJoinV2.sol#L91 https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/singleJoinExit/SingleTokenJoinV2.sol#L100 https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/singleJoinExit/SingleTokenJoinV2.sol#L117

Tools Used

VS Code

Recommended Mitigation Steps

Store the array's length in a variable before the for-loop, and use it instead.

Handle

Dravee

Vulnerability details

Impact

Increased gas costs

Proof of Concept

"constants" expressions are expressions. As such, keccak assigned to a constant variable are re-computed at each use of the variable, which will consume gas unnecessarily. To save gas, Changing the variable from constant to immutable will make the computation run only once and therefore save gas.

Places with the issue: https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/facets/Basket/LibBasketStorage.sol#L7-L8 https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/facets/Call/LibCallStorage.sol#L5-L6 https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/facets/ERC20/LibERC20Storage.sol#L5-L9 https://github.com/code-423n4/2021-12-amun/blob/main/contracts/basket/contracts/facets/shared/Reentry/LibReentryProtectionStorage.sol#L5-L6

Tools Used

VS Code

Recommended Mitigation Steps

Change the variable from constant to immutable