Submitted by hansfriese
https://github.com/code-423n4/2023-02-malt/blob/main/contracts/RewardSystem/LinearDistributor.sol#L147-L151 
https://github.com/code-423n4/2023-02-malt/blob/main/contracts/RewardSystem/LinearDistributor.sol#L185-L186 
https://github.com/code-423n4/2023-02-malt/blob/main/contracts/RewardSystem/LinearDistributor.sol#L123-L136
LinearDistributor.declareReward will revert and it can cause permanent DOS.
In LinearDistributor.declareReward, if the balance is greater than the bufferRequirement, the rest will be forfeited.
And in _forfeit, it requires forfeited (= balance - bufferRequirement) <= declaredBalance.
So when an attacker sends some collateral tokens to LinearDistributor, the balance will be increased and it can cause revert in _forfeit and declareReward.
Since declareReward sends vested amount before _forfeit and the vested amount will be increased by time, so this DOS will be temporary.
But if the attacker increases the balance enough to cover all reward amount in vesting, declareReward will always revert and it can cause permanent DOS.
decrementRewards updates declaredBalance, but it only decreases declaredBalance, so it cant mitigate the DOS.
Track collateral token balance and add sweep logic for unused collateral tokens in LinearDistributor.
Picodes (judge) decreased severity to Medium and commented:
0xScotch (Malt) confirmed and commented:
