code-423n4 / 2022-01-yield-findings

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Gas saving using immutable #42

Open code423n4 opened 2 years ago

code423n4 commented 2 years ago

Handle

0x1f8b

Vulnerability details

Impact

Gas saving.

Proof of Concept

It's possible to avoid storage access a save gas using immutable keyword for the following variables:

ConvexStakingWrapper:

curveToken
convexToken
convexPool
convexPoolId
collateralVault

ConvexYieldWrapper:

cauldron

Tools Used

Gas saving

Recommended Mitigation Steps

Use immutable.

devtooligan commented 2 years ago

Immutable variables cannot be read during contract creation time. Making the suggested variables immutable would lead to https://github.com/code-423n4/2022-01-yield/blob/e946f40239b33812e54fafc700eb2298df1a2579/contracts/ConvexStakingWrapper.sol#L77-L78 to fail.

GalloDaSballo commented 2 years ago

While you can't read immutable variables at creation time, you can use the input from the constructor _curveToken instead of the "storage / immutable" curveToken

Inlining the approvals and using the constructor parameters would solve and save the gas.

I don't mind a nofix from the developer, (although believe there's gas to be saved) but I think the finding is valid

devtooligan commented 2 years ago

@GalloDaSballo Good point. Let me talk to the team