Rock Paper Scissors

Description:

The scoreA and scoreB variables are defined as uint8, limiting each player's score to a maximum value of 255. In games configured with a high number of turns, it's possible for players to reach this limit through a balanced series of wins and ties.

When a player wins an additional round after reaching 255 points, an arithmetic overflow occurs, causing the contract to revert with:

This halts the game permanently, locking any staked ETH or tokens inside the contract.

Impact

• Potential Denial of Service (DoS) in games with excessive turns.

• Permanent locking of staked funds and rewards.

• Game logic failure due to lack of score overflow protection.

Proof of Concept:

A game was executed with 1001 turns (valid since it must be odd). After 766 turns with balanced outcomes, both scores reached 255, triggering the overflow error:

Tools Used

Manual Review and Foundry

Recommendations

Upgrade scoreA and scoreB to uint16 to safely support longer games.
Alternatively, enforce a reasonable maximum limit on the number of turns to avoid unnecessary risk.