add additional basic protective validations on oracle price

Author: dbeal-eth

src/FixedStakingRewards.sol

@@ -17,6 +17,7 @@ error NotEnoughRewards(uint256 available, uint256 required);
 error RewardsNotAvailableYet(uint256 currentTime, uint256 availableTime);
 error CannotWithdrawZero();
 error CannotWithdrawStakingToken(address attemptedToken);
+error InvalidPriceFeed(uint256 updateTime, int256 currentRewardTokenRate);
 
 contract FixedStakingRewards is IStakingRewards, ERC20, ReentrancyGuard, Ownable {
     using SafeERC20 for IERC20;
@@ -156,7 +157,10 @@ contract FixedStakingRewards is IStakingRewards, ERC20, ReentrancyGuard, Ownable
 
     /* ========== INTERNAL FUNCTIONS ========== */
     function _rebalance() internal {
-        (, int256 currentRewardTokenRate, , , ) = rewardsTokenRateAggregator.latestRoundData();
+        (, int256 currentRewardTokenRate, , uint256 updateTime, ) = rewardsTokenRateAggregator.latestRoundData();
+        if (currentRewardTokenRate == 0 || updateTime < block.timestamp - 1 hours) {
+            revert InvalidPriceFeed(updateTime, currentRewardTokenRate);
+        }
         rewardRate = targetRewardApy * 1e18 / (uint256(currentRewardTokenRate) * 10 ** (18 - rewardsTokenRateDecimals)) / 365 days;
     }
 

test/FixedStakingRewards.t.sol

@@ -13,7 +13,8 @@ import {
     NotEnoughRewards,
     RewardsNotAvailableYet,
     CannotWithdrawZero,
-    CannotWithdrawStakingToken
+    CannotWithdrawStakingToken,
+    InvalidPriceFeed
 } from "../src/FixedStakingRewards.sol";
 
 
@@ -172,6 +173,8 @@ contract FixedStakingRewardsTest is Test {
     event Recovered(address token, uint256 amount);
 
     function setUp() public {
+        vm.warp(1000000000);
+
         owner = address(this);
         user1 = makeAddr("user1");
         user2 = makeAddr("user2");
@@ -597,6 +600,7 @@ contract FixedStakingRewardsTest is Test {
         assertEq(earnedAfterRateChange, totalExpectedRewards);
 
         // stake again to make sure rewards are preserved
+        mockAggregator.setLatestAnswer(1e8 / 2, block.timestamp);
         vm.startPrank(user1);
         stakingToken.approve(address(stakingRewards), 200e18);
         stakingRewards.stake(200e18);
@@ -678,6 +682,7 @@ contract FixedStakingRewardsTest is Test {
 
         vm.warp(block.timestamp + 1 days);
 
+        mockAggregator.setLatestAnswer(1e8, block.timestamp);
         stakingRewards.reclaim();
 
         assertEq(rewardsToken.balanceOf(owner), initialBalance + amount);
@@ -762,6 +767,44 @@ contract FixedStakingRewardsTest is Test {
         assertEq(stakingRewards.rewardRate(), 0);
     }
 
+    function test_Rebalance_RevertWhen_PriceFeedReturnsZero() public {
+        // Set target APY
+        stakingRewards.setRewardYieldForYear(1e18);
+        
+        // Set aggregator to return zero rate
+        mockAggregator.setLatestAnswer(0, block.timestamp);
+        
+        // Rebalance should revert with InvalidPriceFeed
+        vm.expectRevert(abi.encodeWithSelector(InvalidPriceFeed.selector, block.timestamp, int256(0)));
+        stakingRewards.rebalance();
+    }
+
+    function test_Rebalance_RevertWhen_PriceFeedIsStale() public {
+        // Set target APY
+        stakingRewards.setRewardYieldForYear(1e18);
+        
+        // Set aggregator with stale data (2 hours old)
+        uint256 staleTimestamp = block.timestamp - 2 hours;
+        mockAggregator.setLatestAnswer(1e8 / 2, staleTimestamp);
+        
+        // Rebalance should revert with InvalidPriceFeed
+        vm.expectRevert(abi.encodeWithSelector(InvalidPriceFeed.selector, staleTimestamp, int256(1e8 / 2)));
+        stakingRewards.rebalance();
+    }
+
+    function test_Rebalance_RevertWhen_PriceFeedIsStaleExactly1Hour() public {
+        // Set target APY
+        stakingRewards.setRewardYieldForYear(1e18);
+        
+        // Set aggregator with data exactly 1 hour old (should still revert)
+        uint256 staleTimestamp = block.timestamp - 1 hours - 1;
+        mockAggregator.setLatestAnswer(1e8 / 2, staleTimestamp);
+        
+        // Rebalance should revert with InvalidPriceFeed
+        vm.expectRevert(abi.encodeWithSelector(InvalidPriceFeed.selector, staleTimestamp, int256(1e8 / 2)));
+        stakingRewards.rebalance();
+    }
+
     /*//////////////////////////////////////////////////////////////
                              MODIFIER TESTS
     //////////////////////////////////////////////////////////////*/