feat(ctb): Prevent `extraData` from being too large in the `OutputBisectionGame` (#8729)

* Prevent `extraData` from being too long for the `OutputBisectionGame`

* semver

packages/contracts-bedrock/semver-lock.json

@@ -100,8 +100,8 @@
     "sourceCodeHash": "0xa995b54dce03ddf5c9c47451bd7181996b91398ad66b54ab0b8cbf582863a33e"
   },
   "src/dispute/OutputBisectionGame.sol": {
-    "initCodeHash": "0xcf6ab94ff4048485d9d13753bb2c49e0af716a50c3d853ad187517a6bdb77070",
-    "sourceCodeHash": "0x2963a04d32929665d1ca31d79b840068de0541d2e6f5e48e5655041b7e406d65"
+    "initCodeHash": "0x10596ff55c460324b6b442fe19d7f849e6dd8202c9b4514ca979ca02be339060",
+    "sourceCodeHash": "0xe0fada6499eb1a24a4e1ccce50568f0b10617dec0fc8af189bff2c9ab4c320ce"
   },
   "src/legacy/DeployerWhitelist.sol": {
     "initCodeHash": "0x8de80fb23b26dd9d849f6328e56ea7c173cd9e9ce1f05c9beea559d1720deb3d",

packages/contracts-bedrock/src/dispute/OutputBisectionGame.sol

@@ -81,8 +81,8 @@ contract OutputBisectionGame is IOutputBisectionGame, Clone, ISemver {
     bool internal subgameAtRootResolved;
 
     /// @notice Semantic version.
-    /// @custom:semver 0.0.17
-    string public constant version = "0.0.17";
+    /// @custom:semver 0.0.18
+    string public constant version = "0.0.18";
 
     /// @param _gameType The type ID of the game.
     /// @param _absolutePrestate The absolute prestate of the instruction trace.
@@ -454,6 +454,19 @@ contract OutputBisectionGame is IOutputBisectionGame, Clone, ISemver {
         // Set the game's starting timestamp
         createdAt = Timestamp.wrap(uint64(block.timestamp));
 
+        // Revert if the calldata size is too large, which signals that the `extraData` contains more than expected.
+        // This is to prevent adding extra bytes to the `extraData` that result in a different game UUID in the factory,
+        // but are not used by the game, which would allow for multiple dispute games for the same output proposal to
+        // be created.
+        // Expected length: 0x46 (0x04 selector + 0x20 root claim + 0x20 extraData + 0x02 CWIA bytes)
+        assembly {
+            if gt(calldatasize(), 0x46) {
+                // Store the selector for `ExtraDataTooLong()` & revert
+                mstore(0x00, 0xc407e025)
+                revert(0x1C, 0x04)
+            }
+        }
+
         // Set the root claim
         claimData.push(
             ClaimData({

packages/contracts-bedrock/src/libraries/DisputeErrors.sol

@@ -28,6 +28,9 @@ error UnexpectedRootClaim(Claim rootClaim);
 ///         cost of the next possible counter claim.
 error BondTooLow();
 
+/// @notice Thrown when the `extraData` passed to the CWIA proxy is too long for the `FaultDisputeGame`.
+error ExtraDataTooLong();
+
 /// @notice Thrown when a defense against the root claim is attempted.
 error CannotDefendRootClaim();
 

packages/contracts-bedrock/test/dispute/OutputBisectionGame.t.sol

@@ -168,6 +168,28 @@ contract OutputBisectionGame_Test is OutputBisectionGame_Init {
         gameProxy = OutputBisectionGame(address(factory.create(GAME_TYPE, claim, abi.encode(_blockNumber))));
     }
 
+    /// @dev Tests that the game cannot be initialized with extra data > 64 bytes long (root claim + l2 block number
+    ///      concatenated)
+    function testFuzz_initialize_extraDataTooLong_reverts(uint256 _extraDataLen) public {
+        // The `DisputeGameFactory` will pack the root claim and the extra data into a single array, which is enforced
+        // to be at least 64 bytes long.
+        // We bound the upper end to 23.5KB to ensure that the minimal proxy never surpasses the contract size limit
+        // in this test, as CWIA proxies store the immutable args in their bytecode.
+        // [33 bytes, 23.5 KB]
+        _extraDataLen = bound(_extraDataLen, 33, 23_500);
+        bytes memory _extraData = new bytes(_extraDataLen);
+
+        // Assign the first 32 bytes in `extraData` to a valid L2 block number passed genesis.
+        uint256 genesisBlockNumber = gameProxy.genesisBlockNumber();
+        assembly {
+            mstore(add(_extraData, 0x20), add(genesisBlockNumber, 1))
+        }
+
+        Claim claim = _dummyClaim();
+        vm.expectRevert(abi.encodeWithSelector(ExtraDataTooLong.selector));
+        gameProxy = OutputBisectionGame(address(factory.create(GAME_TYPE, claim, _extraData)));
+    }
+
     /// @dev Tests that the game is initialized with the correct data.
     function test_initialize_correctData_succeeds() public {
         // Assert that the root claim is initialized correctly.