Beanstalk: The Finale
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Submission Details
Severity: low
Invalid

Division by Zero Error in LibUnripe.sol underlyingToUnripe Function

kevinkkien

Summary

The LibUnripe.sol library in the Beanstalk project contains a potential division by zero vulnerability in the underlyingToUnripe function. This error occurs when s.sys.silo.unripeSettings[unripeToken].balanceOfUnderlying (the balance of the underlying token in the Unripe Token) is 0, leading to division by zero and causing transaction reverts.

Vulnerability Details

The underlyingToUnripe function in LibUnripe.sol calculates the amount of Unripe Tokens corresponding to a given amount of Ripe Tokens. However, the function does not check if the value of s.sys.silo.unripeSettings[unripeToken].balanceOfUnderlying is 0 before performing the division:

function underlyingToUnripe(
address unripeToken,
uint256 underlying
) internal view returns (uint256 unripe) {
AppStorage storage s = LibAppStorage.diamondStorage();
unripe = IBean(unripeToken).totalSupply().mul(underlying).div(
s.sys.silo.unripeSettings[unripeToken].balanceOfUnderlying // Could be 0
);
}

If s.sys.silo.unripeSettings[unripeToken].balanceOfUnderlying is 0, this division will cause a division by zero error and revert the transaction.

Impact

If a user attempts to call the underlyingToUnripe function with an Unripe Token that has a 0 underlying token balance, the transaction will revert, causing the user to waste gas.

Tools Used

Manual Code Review

Recommendations

require check should be added to ensure that s.sys.silo.unripeSettings[unripeToken].balanceOfUnderlying is not 0 before performing the division:

function underlyingToUnripe(
address unripeToken,
uint256 underlying
) internal view returns (uint256 unripe) {
AppStorage storage s = LibAppStorage.diamondStorage();
​
// Check underlying token balance
require(
s.sys.silo.unripeSettings[unripeToken].balanceOfUnderlying > 0,
"LibUnripe: Division by zero"
);
​
unripe = IBean(unripeToken).totalSupply().mul(underlying).div(
s.sys.silo.unripeSettings[unripeToken].balanceOfUnderlying
);
}
Updates

Lead Judging Commences

inallhonesty Lead Judge about 1 year ago
Submission Judgement Published
Invalidated
Reason: Non-acceptable severity
Assigned finding tags:

Informational/Gas

Invalid as per docs https://docs.codehawks.com/hawks-auditors/how-to-determine-a-finding-validity

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