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code-423n4 / 2021-12-yetifinance-findings

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Cache array length in for loops can save gas #165

Closed code423n4 closed 2 years ago

code423n4 commented 2 years ago

Handle

defsec

Vulnerability details

Impact

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.

Proof of Concept

  1. Navigate to the following smart contract line.
https://github.com/code-423n4/2021-12-yetifinance/blob/1da782328ce4067f9654c3594a34014b0329130a/packages/contracts/contracts/BorrowerOperations.sol#L699

https://github.com/code-423n4/2021-12-yetifinance/blob/1da782328ce4067f9654c3594a34014b0329130a/packages/contracts/contracts/BorrowerOperations.sol#L873

https://github.com/code-423n4/2021-12-yetifinance/blob/1da782328ce4067f9654c3594a34014b0329130a/packages/contracts/contracts/BorrowerOperations.sol#L920

https://github.com/code-423n4/2021-12-yetifinance/blob/1da782328ce4067f9654c3594a34014b0329130a/packages/contracts/contracts/BorrowerOperations.sol#L929

https://github.com/code-423n4/2021-12-yetifinance/blob/1da782328ce4067f9654c3594a34014b0329130a/packages/contracts/contracts/ActivePool.sol#L167

Tools Used

None

Recommended Mitigation Steps

Consider to cache array length.

kingyetifinance commented 2 years ago

@LilYeti: Duplicate #14

alcueca commented 2 years ago

Duplicate #283