Beanstalk Part 1

Summary

In LibUnripe:switchUnderlyingToken there is a missing must condition that the balance of underlying of unripe token should be zero before switching underlying token s.u[unripeToken].balanceOfUnderlying == 0.

Vulnerability Details

Although some functions calling it have checked the condition there is 1 function in InitMigrateUnripeBean3CrvToBeanEth that has left it. Also if there are more functionalities which will need this function its highly possible that this check will be missed.

Impact

Without this validation, it could lead to unexpected behavior or inconsistencies in the underlying token switching process, and if there is some balance. That will be lost during the switching.

Tools Used

Manual Review

Recommendations

Apply this condition require(s.u[unripeToken].balanceOfUnderlying == 0, "Unripe: Underlying balance > 0"); in the start of switchUnderlyingToken to resolve the issue.