Fjord Token Staking

Summary

In FjordStaking contract

Vulnerability Details

In FjordStaking::_redeem when calculateReward function is called, last parameter - _toEpoch is set to be currentEpoch - 1 :

As currentEpoch is set to 1 in the constructor that makes function calculateReward to be called with a 0 as last parameter.

As 0 is not a valid epoch function will either calculate wrong value or most probably revert as uint cannot be negative. That causes bigger issue as redeemPendingRewards modifier also reverts and currentEpoch is never changed as the only function that changes it is checkEpochRollover which changes are not saved as it is used always with redeemPendingRewards which will revert.

Impact

The whole contract will become unusable.

Tools Used

Manual Review

Recommendations

Add checks to ensure that currentEpoch - 1 > 0