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code-423n4 / 2021-06-gro-findings

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Stricter than needed inequalities may affect borderline scenarios #67

Open code423n4 opened 3 years ago

code423n4 commented 3 years ago

Handle

0xRajeev

Vulnerability details

Impact

Token amounts/prices are typically open-ranged and inclusive of the bounds. Using ‘<‘ or ‘>’ instead of ‘<=‘ and ‘>=‘ may affect borderline scenarios, considered unintuitive by users and affect accounting.

Scenario 1: In calculateVaultSwapData(), the require() check is: require(withdrawAmount < state.totalCurrentAssetsUsd, "Withdrawal exceeds system assets"); The ‘<‘ could be replaced by ‘<=‘

Scenario 2: In withdrawSingleByLiquidity(), the require() check is: require(balance > minAmount, "withdrawSingle: !minAmount"); The ‘>’ should be ‘>=‘ as is used in the similar check in withdrawSingleByExchange().

Proof of Concept

https://github.com/code-423n4/2021-06-gro/blob/091660467fc8d13741f8aafcec80f1e8cf129a33/contracts/insurance/Insurance.sol#L429

https://github.com/code-423n4/2021-06-gro/blob/091660467fc8d13741f8aafcec80f1e8cf129a33/contracts/pools/LifeGuard3Pool.sol#L224

https://github.com/code-423n4/2021-06-gro/blob/091660467fc8d13741f8aafcec80f1e8cf129a33/contracts/pools/LifeGuard3Pool.sol#L268

Tools Used

Manual Analysis

Recommended Mitigation Steps

Reconsider strict inequalities and relax them if possible.

kitty-the-kat commented 3 years ago

We haven't been able to model an exploit for this