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Unnecessary checked arithmetic in for loops #28

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code423n4 opened this issue Oct 9, 2021 · 1 comment
Open

Unnecessary checked arithmetic in for loops #28

code423n4 opened this issue Oct 9, 2021 · 1 comment
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bug Warden finding G (Gas Optimization) sponsor acknowledged Technically the issue is correct, but we're not going to resolve it for XYZ reasons

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@code423n4
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Handle

pants

Vulnerability details

There is no risk of overflow caused by increaments to the iteration index in for loops (the i++ in for (uint256 i = 0; i < numIterations; i++)).

Impact

Increaments perform overflow checks that are not necessary in this case.

Tool Used

Manual code review.

Recommended Mitigation Steps

Surround the increament expressions with an unchecked { ... } block to avoid the default overflow checks. For example, change the loop

for (uint256 i = 0; i < numIterations; i++) {
	// ...
}

to

for (uint256 i = 0; i < numIterations;) {
	// ...
	unchecked { i++; }
}

It is a little less readable but it saves a significant amount of gas.

code423n4 added a commit that referenced this issue Oct 9, 2021
@frank-beard frank-beard added the sponsor acknowledged Technically the issue is correct, but we're not going to resolve it for XYZ reasons label Nov 6, 2021
@GalloDaSballo
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Agree with the improvement

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Labels
bug Warden finding G (Gas Optimization) sponsor acknowledged Technically the issue is correct, but we're not going to resolve it for XYZ reasons
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