Submitted by xuwinnie, also found by Ch_301
When the required stake (to create a new assertions) is updated to a lower amount, adversary can make the honest party unable to retrieve their assertion stakes.
Suppose the initial stake amount is 1000 ETH, and till now no invalid assertions have been made. (A, B, C, D, E are all valid and made by the same validator). The rollup contract should hold 1000 ETH now.
Then, the admin update the required stake to 700 ETH, Alice made an invalid assertion F. Since its parent D was created before the update, Alice will still need to stake 1000 ETH, and the 1000 ETH will be sent to loserStakeEscrow.
(a) Alice creates Fs children, G. Now, only 700 ETH of stake is needed. However, as the comment suggests, no refund will be made since Gs ancestor could need more stake.
(b) To bypass the limit in (a), Alice calls her friend Bob to make the assertion G instead , Bob will only need to stake 700 ETH now. The rollup contract currently holds 1700 ETH. Then, Alice can withdraw her stake since she is no longer active. (her last staked assertion have a child)
Now the rollup contract holds 700 ETH, which means it is insolvent. The honest validator cannot withdraw her original stake. (700 < 1000)
Ensure the following
gzeoneth (Arbitrum) confirmed and commented:
