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sherlock-audit / 2023-01-uxd-judging

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JohnnyTime - The `_abs` function in the `PerpDepository.sol` is useless since there are no negative numbers in Solidity #413

Closed github-actions[bot] closed 1 year ago

github-actions[bot] commented 1 year ago

JohnnyTime

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The _abs function in the PerpDepository.sol is useless since there are no negative numbers in Solidity

Summary

In solidity we have only unsigned integers which means we can't have negative numbers, there is no reason to convert a number to it's "Absolute" version, since it could either be 0 or greater than 0, it can't be negative (-).

Vulnerability Detail

The _abs function in PerpDepository.sol is supposed to return the "absolute" value of a number. It's useless and doesn't make sense because we don't have negative numbers in solidity. In case the input number is 0 it returns uint256(-1 * value), which will revert since you can't use negative numbers in solidity. _abs is used in multiple places in the contract, which wastes a lot of gas, in addition if the value that will be sent to the function will be 0, it will be reverted due to the usage of -1. _abs(0) ==> always reverts.

Impact

Dos for the contract when _abs(0), and a lot of wasted gas anytime we call this function.

Code Snippet

https://github.com/sherlock-audit/2023-01-uxd/blob/main/contracts/integrations/perp/PerpDepository.sol#L821-L823 https://github.com/sherlock-audit/2023-01-uxd/blob/main/contracts/integrations/perp/PerpDepository.sol#L521 https://github.com/sherlock-audit/2023-01-uxd/blob/main/contracts/integrations/perp/PerpDepository.sol#L684 https://github.com/sherlock-audit/2023-01-uxd/blob/main/contracts/integrations/perp/PerpDepository.sol#L712 https://github.com/sherlock-audit/2023-01-uxd/blob/main/contracts/integrations/perp/PerpDepository.sol#L781

Tool used

Manual Review

Recommendation

Get rid of the _abs function.