ltyu - Carousel vaults without any deposits will lose emissions

[sherlock-admin]

ltyu

high

Carousel vaults without any deposits will lose emissions

Summary

Carousels that have emissions that end as null events, will cause one/both side(s) to lose emissions tokens.

Vulnerability Detail

When a Carousel is created, it can have emissions added to the epoch. Currently, when the epoch ends (with/out a depeg event), the depositors can claim their share of emissions. However, when there are no depositors for that epoch, emissions cannot be claimed. This is resolved as a null epoch. No one will have the epoch's tokens to burn and claim the emissions (done within withdraw()).

Impact

This is high impact because emission tokens will be lost in null epoch. Currently, there is no way to recover unclaimed tokens.

Code Snippet

Emission tokens are added:
https://github.com/sherlock-audit/2023-03-Y2K/blob/main/Earthquake/src/v2/Carousel/CarouselFactory.sol#L132-L153

Emission tokens are calculated upon withdraw(). If there is a null epoch, no one will have that epoch's tokens, burns will revert, and thus emissions cannot be claimed:
https://github.com/sherlock-audit/2023-03-Y2K/blob/main/Earthquake/src/v2/Carousel/Carousel.sol#L154-L157

https://github.com/sherlock-audit/2023-03-Y2K/blob/main/Earthquake/src/v2/Carousel/Carousel.sol#L630-L636

Tool used

Manual Review

Recommendation

Consider allowing emissions to be reclaimed by treasury, or possibly, rolled over to another epoch.

Duplicate of #122