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code-423n4 / 2021-07-pooltogether-findings

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Caching the result of an external call can save 2600 gas #35

Closed code423n4 closed 3 years ago

code423n4 commented 3 years ago

Handle

0xRajeev

Vulnerability details

Impact

In _setYieldSource() a call to _newYieldSource.depositToken() is made twice. Caching the return value in a local variable can prevent an extra CALL saving 2600 gas.

Proof of Concept

https://github.com/pooltogether/swappable-yield-source/blob/89cf66a3e3f8df24a082e1cd0a0e80d08953049c/contracts/SwappableYieldSource.sol#L256

https://github.com/pooltogether/swappable-yield-source/blob/89cf66a3e3f8df24a082e1cd0a0e80d08953049c/contracts/SwappableYieldSource.sol#L259

Tools Used

Manual Analysis

Recommended Mitigation Steps

Cache return value of _newYieldSource.depositToken() in a local variable and use that on L259.

PierrickGT commented 3 years ago

Duplicate of https://github.com/code-423n4/2021-07-pooltogether-findings/issues/26