Submission Details
Severity:
Potential Reentrancy Vulnerability
Summary
The function _updatePrice calls an external contract (IScrvusdOracle(SCRVUSD_ORACLE).update_price(params, ts, number)). If update_price is not protected against reentrancy (like by using a reentrancy guard or following the checks-effects-interactions pattern), it may allow an attacker to call back into your contract and manipulate its state in unintended ways during the execution of _updatePrice.
Vulnerability Details
Impact
Tools Used
Recommendations
// SPDX-License-Identifier: MIT
import {RLPReader} from "hamdiallam/Solidity-RLP@2.0.7/contracts/RLPReader.sol";
import {StateProofVerifier as Verifier} from "../../xdao/contracts/libs/StateProofVerifier.sol";
import "@openzeppelin/contracts/security/ReentrancyGuard.sol";
uint256 constant PARAM_CNT = 2 + 5;
uint256 constant PROOF_CNT = 1 + PARAM_CNT;
interface IScrvusdOracle {
function update_price(
uint256[PARAM_CNT] memory _parameters,
uint256 _ts,
uint256 _block_number
) external returns (uint256);
}
interface IBlockHashOracle {
function get_block_hash(uint256 _number) external view returns (bytes32);
function get_state_root(uint256 _number) external view returns (bytes32);
}
contract ScrvusdVerifierV1 is ReentrancyGuard {
using RLPReader for bytes;
using RLPReader for RLPReader.RLPItem;
// Common constants
address constant SCRVUSD = 0x0655977FEb2f289A4aB78af67BAB0d17aAb84367;
bytes32 constant SCRVUSD_HASH = keccak256(abi.encodePacked(SCRVUSD));
// Storage slots of parameters
uint256[PROOF_CNT] internal PARAM_SLOTS = [
uint256(0), // filler for account proof
uint256(21), // total_debt
uint256(22), // total_idle
uint256(20), // totalSupply
uint256(38), // full_profit_unlock_date
uint256(39), // profit_unlocking_rate
uint256(40), // last_profit_update
uint256(keccak256(abi.encode(18, SCRVUSD))) // balanceOf(self)
];
address public immutable SCRVUSD_ORACLE;
address public immutable BLOCK_HASH_ORACLE;
constructor(address _block_hash_oracle, address _scrvusd_oracle)
{
BLOCK_HASH_ORACLE = _block_hash_oracle;
SCRVUSD_ORACLE = _scrvusd_oracle;
}
/// @param _block_header_rlp The RLP-encoded block header
/// @param _proof_rlp The state proof of the parameters
function verifyScrvusdByBlockHash(
bytes memory _block_header_rlp,
bytes memory _proof_rlp
) external returns (uint256) {
Verifier.BlockHeader memory block_header = Verifier.parseBlockHeader(_block_header_rlp);
require(block_header.hash != bytes32(0), "Invalid blockhash");
require(
block_header.hash == IBlockHashOracle(BLOCK_HASH_ORACLE).get_block_hash(block_header.number),
"Blockhash mismatch"
);
uint256[PARAM_CNT] memory params = _extractParametersFromProof(block_header.stateRootHash, _proof_rlp);
return _updatePrice(params, block_header.timestamp, block_header.number);
}
/// @param _block_number Number of the block to use state root hash
/// @param _proof_rlp The state proof of the parameters
function verifyScrvusdByStateRoot(
uint256 _block_number,
bytes memory _proof_rlp
) external returns (uint256) {
bytes32 state_root = IBlockHashOracle(BLOCK_HASH_ORACLE).get_state_root(_block_number);
uint256[PARAM_CNT] memory params = _extractParametersFromProof(state_root, _proof_rlp);
// Use last_profit_update as the timestamp surrogate
return _updatePrice(params, params[5], _block_number);
}
/// @dev Extract parameters from the state proof using the given state root.
function _extractParametersFromProof(
bytes32 stateRoot,
bytes memory proofRlp
) internal view returns (uint256[PARAM_CNT] memory) {
RLPReader.RLPItem[] memory proofs = proofRlp.toRlpItem().toList();
require(proofs.length == PROOF_CNT, "Invalid number of proofs");
// Extract account proof
Verifier.Account memory account = Verifier.extractAccountFromProof(
SCRVUSD_HASH,
stateRoot,
proofs[0].toList()
);
require(account.exists, "scrvUSD account does not exist");
// Extract slot values
uint256[PARAM_CNT] memory params;
for (uint256 i = 1; i < PROOF_CNT; i++) {
Verifier.SlotValue memory slot = Verifier.extractSlotValueFromProof(
keccak256(abi.encode(PARAM_SLOTS[i])),
account.storageRoot,
proofs[i].toList()
);
// Slots might not exist, but typically we just read them.
params[i - 1] = slot.value;
}
return params;
}
/// @dev Calls the oracle to update the price parameters.
/// Both child contracts use the same oracle call, differing only in how they obtain the timestamp.
function _updatePrice(
uint256[PARAM_CNT] memory params,
uint256 ts,
uint256 number
) internal nonReentrant returns (uint256) {
return IScrvusdOracle(SCRVUSD_ORACLE).update_price(params, ts, number);
}
}
Prize pool breakdown
Total prize
14,723 OP
Eagles
1,472 OP
nSLOC
39437 OP / LOC
12,700
551
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