sherlock-admin
commented
1 year ago 4 comment(s) were left on this issue during the judging contest.
panprog commented:
invalid because price can't change in the same transaction between these functions, and even if it could, market.update will simply revert
n33k commented:
invalid, not convincing without PoC
darkart commented:
Not clearly writen vulnerability
polarzero commented:
High. This could easily be manipulated repeatedly to drain the funds of the contract.
feelereth
high
Doesn't validate account is actually undercollateralized before liquidating. Price could fluctuate between checks.
Summary
Doesn't validate account is actually undercollateralized before liquidating. Price could fluctuate between checks. Should verify current collateralization.
Vulnerability Detail
The key lines are in the _liquidate function. It computes the liquidation fee and closable amount based on the latest price via _liquidationFee, but does not re-check the collateralization at the time of liquidation. This is problematic because: • The price could move between _liquidationFee and market.update • An account's collateralization ratio could go from under to overcollateralized • But its position would still get closed and charged a fee incorrectly
Impact
Improper liquidations if the price changes.
Code Snippet
https://github.com/sherlock-audit/2023-09-perennial/blob/main/perennial-v2/packages/perennial-extensions/contracts/MultiInvoker.sol#L226-L240
Tool used
Manual Review
Recommendation
_liquidate should re-check collateralization at the time of liquidation. This verifies the account is still undercollateralized at the time of liquidation, preventing improper liquidations if the price changes.