Fjord Token Staking

Description

The FjordStaking::unstake function is intended to allow users to unstake their tokens while also claiming any pending rewards. According to the documentation, users should be able to unstake tokens early by bypassing the reward cooldown period of 3 epochs, incurring a penalty. However, the current implementation does not provide this functionality. Instead, it strictly enforces the lock cycle and prevents any unstaking before the cycle is complete, which contradicts the documented behavior.

Additionally, the NatSpec comments mention a _isEarly parameter that should allow users to bypass the lock cycle with a penalty. However, this parameter does not exist in the function’s signature or implementation, further deviating from the documented intent and potentially misleading users and developers.

Impact

This issue has a high severity because it directly impacts the user experience and contract functionality. Users are unable to claim rewards and unstake their tokens simultaneously, which might lead to a lack of trust in the protocol and potential financial losses if users are forced to keep their tokens locked for longer than expected. The discrepancy between the documentation and the actual implementation also increases the risk of incorrect usage or reliance on non-existent features.

Proof of Concepts

The following code snippet from the FjordStaking::unstake function illustrates the issue:

The above code enforces the lock cycle strictly, preventing any unstaking before the lock cycle is complete. This contradicts the documented functionality that suggests users can claim reward early with a penalty.

Furthermore, the NatSpec documentation suggests a non-existent _isEarly parameter should allow users to bypass the rewards cooldown:

This _isEarly parameter is not implemented, leading to further confusion and misalignment between the code and its documentation.

In contrast, the FjordStaking::claimReward function includes logic for handling early claims with a penalty:

The FjordStaking::claimReward function allows users to claim rewards early with a penalty, but similar functionality is missing in the unstake function, making it impossible to claim rewards and unstake simultaneously under the conditions implied by the documentation.

Recommended Mitigation

1. Code Modification: Update the FjordStaking::unstake function to include a similar penalty mechanism as found in FjordStaking::claimReward. This would involve checking whether the unstake is occurring within the lock cycle, applying a penalty to the rewards, and allowing the unstake to proceed.

2. Parameter Implementation: Consider implementing the _isEarly parameter as suggested in the documentation, ensuring that users can choose to unstake early with the corresponding penalty applied.

3. Documentation Update: If strict enforcement of the lock cycle is the intended behavior, update the documentation to reflect this. The documentation should clearly state that early unstaking is not allowed under any circumstances, thereby avoiding any confusion for the users.