Submitted by 0x52
Trade delay will not work correctly on Arbitrum allowing users to exploit multiple valid prices.
\_checkDelay enforces a delay of a specific number of block between opening and closing a position. While this structure will work on mainnet, it is problematic for use on Arbitrum. 
According to Arbitrum Docs block.number returns the most recently synced L1 block number. Once per minute the block number in the Sequencer is synced to the actual L1 block number. This period could be abused to completely bypass this protection. 
The user would open their position 1 Arbitrum block before the sync happens, then close it the very next block. It would appear that there has been 5 blocks (60 / 12) since the last transaction but in reality it has only been 1 Arbitrum block. Given that Arbitrum has 2 seconds blocks it would be impossible to block this behavior through parameter changes.
It also presents an issue for Optimism because each transaction is its own block. No matter what value is used for the block delay, the user can pad enough tiny transactions to allow them to close the trade immediately.
The delay should be measured using block.timestamp rather than block.number.
TriHaz (Tigris Trade) disputed and commented:
Alex the Entreprenerd (judge) decreased severity to Medium and commented:
Alex the Entreprenerd (judge) commented:
GainsGoblin (Tigris Trade) confirmed and resolved:
