Use asset values instead of asset prices in oracle calls

src/Morpho.sol

@@ -344,9 +344,7 @@ contract Morpho is IMorpho {
 
         _accrueInterest(marketParams, id);
 
-        uint256 collateralPrice = IOracle(marketParams.oracle).price();
-
-        require(!_isHealthy(marketParams, id, borrower, collateralPrice), ErrorsLib.HEALTHY_POSITION);
+        require(!_isHealthy(marketParams, id, borrower), ErrorsLib.HEALTHY_POSITION);
 
         uint256 repaidAssets;
         {
@@ -357,13 +355,19 @@ contract Morpho is IMorpho {
             );
 
             if (seizedAssets > 0) {
-                repaidAssets =
-                    seizedAssets.mulDivUp(collateralPrice, ORACLE_PRICE_SCALE).wDivUp(liquidationIncentiveFactor);
+                repaidAssets = IOracle(marketParams.oracle).value(
+                    marketParams.collateralToken,
+                    marketParams.loanToken,
+                    seizedAssets
+                ).wDivUp(liquidationIncentiveFactor);
                 repaidShares = repaidAssets.toSharesDown(market[id].totalBorrowAssets, market[id].totalBorrowShares);
             } else {
                 repaidAssets = repaidShares.toAssetsUp(market[id].totalBorrowAssets, market[id].totalBorrowShares);
-                seizedAssets =
-                    repaidAssets.wMulDown(liquidationIncentiveFactor).mulDivDown(ORACLE_PRICE_SCALE, collateralPrice);
+                seizedAssets = IOracle(marketParams.oracle).value(
+                    marketParams.loanToken,
+                    marketParams.collateralToken,
+                    repaidAssets.wMulDown(liquidationIncentiveFactor)
+                );
             }
         }
 
@@ -480,28 +484,19 @@ contract Morpho is IMorpho {
 
     /// @dev Returns whether the position of `borrower` in the given market `marketParams` is healthy.
     /// @dev Assumes that the inputs `marketParams` and `id` match.
+    /// @dev Rounds in favor of the protocol, so one might not be able to borrow exactly `maxBorrow` but one unit less.
     function _isHealthy(MarketParams memory marketParams, Id id, address borrower) internal view returns (bool) {
         if (position[id][borrower].borrowShares == 0) return true;
-
-        uint256 collateralPrice = IOracle(marketParams.oracle).price();
-
-        return _isHealthy(marketParams, id, borrower, collateralPrice);
-    }
-
-    /// @dev Returns whether the position of `borrower` in the given market `marketParams` with the given
-    /// `collateralPrice` is healthy.
-    /// @dev Assumes that the inputs `marketParams` and `id` match.
-    /// @dev Rounds in favor of the protocol, so one might not be able to borrow exactly `maxBorrow` but one unit less.
-    function _isHealthy(MarketParams memory marketParams, Id id, address borrower, uint256 collateralPrice)
-        internal
-        view
-        returns (bool)
-    {
         uint256 borrowed = uint256(position[id][borrower].borrowShares).toAssetsUp(
             market[id].totalBorrowAssets, market[id].totalBorrowShares
         );
-        uint256 maxBorrow = uint256(position[id][borrower].collateral).mulDivDown(collateralPrice, ORACLE_PRICE_SCALE)
-            .wMulDown(marketParams.lltv);
+
+        uint256 collateralValue = IOracle(marketParams.oracle).value(
+            marketParams.collateralToken,
+            marketParams.loanToken,
+            uint256(position[id][borrower].collateral
+        ));
+        uint256 maxBorrow = collateralValue.wMulDown(marketParams.lltv);
 
         return maxBorrow >= borrowed;
     }

src/interfaces/IOracle.sol

@@ -11,4 +11,7 @@ interface IOracle {
     /// 10**(loan token decimals) assets of loan token with `36 + loan token decimals - collateral token decimals`
     /// decimals of precision.
     function price() external view returns (uint256);
+
+    /// @notice Returns the value of an amount of base token in terms of quote token.
+    function value(address baseToken, address quoteToken, uint256 baseAmount) external view returns (uint256 quoteAmount);
 }

src/mocks/OracleMock.sol

@@ -2,11 +2,27 @@
 pragma solidity ^0.8.0;
 
 import {IOracle} from "../interfaces/IOracle.sol";
+import {SharesMathLib} from "../libraries/SharesMathLib.sol";
+import {MathLib} from "../libraries/MathLib.sol";
+import "../libraries/ConstantsLib.sol";
 
 contract OracleMock is IOracle {
+    using SharesMathLib for uint256;
+    using MathLib for uint256;
+
+    address public loanToken;
+    address public collateralToken;
     uint256 public price;
 
-    function setPrice(uint256 newPrice) external {
+    function setPrice(address newLoanToken, address newCollateralToken, uint256 newPrice) external {
+        loanToken = newLoanToken;
+        collateralToken = newCollateralToken;
         price = newPrice;
     }
+
+    // In _isHealthy, we value collateral tokens in loan token terms, so collateral is base and loan is quote.
+    function value(address baseToken, address quoteToken, uint256 baseAmount) public view override returns (uint256 quoteAmount) {
+        if (baseToken == loanToken && quoteToken == collateralToken) quoteAmount = price.mulDivDown(ORACLE_PRICE_SCALE, baseAmount);
+        if (baseToken == collateralToken && quoteToken == loanToken) quoteAmount = baseAmount.mulDivDown(price, ORACLE_PRICE_SCALE);
+    }
 }

test/forge/BaseTest.sol

@@ -76,7 +76,7 @@ contract BaseTest is Test {
 
         oracle = new OracleMock();
 
-        oracle.setPrice(ORACLE_PRICE_SCALE);
+        oracle.setPrice(address(loanToken), address(collateralToken), ORACLE_PRICE_SCALE);
 
         irm = new IrmMock();
 

test/forge/integration/BorrowIntegrationTest.sol

@@ -72,7 +72,7 @@ contract BorrowIntegrationTest is BaseTest {
         amountSupplied = bound(amountSupplied, amountBorrowed, MAX_TEST_AMOUNT);
         _supply(amountSupplied);
 
-        oracle.setPrice(priceCollateral);
+        oracle.setPrice(address(loanToken), address(collateralToken), priceCollateral);
 
         collateralToken.setBalance(BORROWER, amountCollateral);
 
@@ -95,7 +95,7 @@ contract BorrowIntegrationTest is BaseTest {
         amountSupplied = bound(amountSupplied, 1, amountBorrowed - 1);
         _supply(amountSupplied);
 
-        oracle.setPrice(priceCollateral);
+        oracle.setPrice(address(loanToken), address(collateralToken), priceCollateral);
 
         collateralToken.setBalance(BORROWER, amountCollateral);
 
@@ -118,7 +118,7 @@ contract BorrowIntegrationTest is BaseTest {
         amountSupplied = bound(amountSupplied, amountBorrowed, MAX_TEST_AMOUNT);
         _supply(amountSupplied);
 
-        oracle.setPrice(priceCollateral);
+        oracle.setPrice(address(loanToken), address(collateralToken), priceCollateral);
 
         collateralToken.setBalance(BORROWER, amountCollateral);
 
@@ -161,7 +161,7 @@ contract BorrowIntegrationTest is BaseTest {
         amountSupplied = bound(amountSupplied, expectedAmountBorrowed, MAX_TEST_AMOUNT);
         _supply(amountSupplied);
 
-        oracle.setPrice(priceCollateral);
+        oracle.setPrice(address(loanToken), address(collateralToken), priceCollateral);
 
         collateralToken.setBalance(BORROWER, amountCollateral);
 
@@ -195,7 +195,7 @@ contract BorrowIntegrationTest is BaseTest {
         amountSupplied = bound(amountSupplied, amountBorrowed, MAX_TEST_AMOUNT);
         _supply(amountSupplied);
 
-        oracle.setPrice(priceCollateral);
+        oracle.setPrice(address(loanToken), address(collateralToken), priceCollateral);
 
         collateralToken.setBalance(ONBEHALF, amountCollateral);
 
@@ -241,7 +241,7 @@ contract BorrowIntegrationTest is BaseTest {
         amountSupplied = bound(amountSupplied, expectedAmountBorrowed, MAX_TEST_AMOUNT);
         _supply(amountSupplied);
 
-        oracle.setPrice(priceCollateral);
+        oracle.setPrice(address(loanToken), address(collateralToken), priceCollateral);
 
         collateralToken.setBalance(ONBEHALF, amountCollateral);
 

test/forge/integration/CallbacksIntegrationTest.sol

@@ -126,7 +126,7 @@ contract CallbacksIntegrationTest is
         uint256 collateralAmount;
         (collateralAmount, loanAmount,) = _boundHealthyPosition(0, loanAmount, oracle.price());
 
-        oracle.setPrice(ORACLE_PRICE_SCALE);
+        oracle.setPrice(address(loanToken), address(collateralToken), ORACLE_PRICE_SCALE);
 
         loanToken.setBalance(address(this), loanAmount);
         collateralToken.setBalance(address(this), collateralAmount);
@@ -147,7 +147,7 @@ contract CallbacksIntegrationTest is
         uint256 collateralAmount;
         (collateralAmount, loanAmount,) = _boundHealthyPosition(0, loanAmount, oracle.price());
 
-        oracle.setPrice(ORACLE_PRICE_SCALE);
+        oracle.setPrice(address(loanToken), address(collateralToken), ORACLE_PRICE_SCALE);
 
         loanToken.setBalance(address(this), loanAmount);
         collateralToken.setBalance(address(this), collateralAmount);
@@ -156,7 +156,7 @@ contract CallbacksIntegrationTest is
         morpho.supplyCollateral(marketParams, collateralAmount, address(this), hex"");
         morpho.borrow(marketParams, loanAmount, 0, address(this), address(this));
 
-        oracle.setPrice(0.99e18);
+        oracle.setPrice(address(loanToken), address(collateralToken), 0.99e18);
 
         loanToken.setBalance(address(this), loanAmount);
         loanToken.approve(address(morpho), 0);
@@ -173,7 +173,7 @@ contract CallbacksIntegrationTest is
         uint256 collateralAmount;
         (collateralAmount, loanAmount,) = _boundHealthyPosition(0, loanAmount, oracle.price());
 
-        oracle.setPrice(ORACLE_PRICE_SCALE);
+        oracle.setPrice(address(loanToken), address(collateralToken), ORACLE_PRICE_SCALE);
 
         loanToken.setBalance(address(this), loanAmount);
         morpho.supply(marketParams, loanAmount, 0, address(this), hex"");

test/forge/integration/LiquidateIntegrationTest.sol

@@ -51,7 +51,7 @@ contract LiquidateIntegrationTest is BaseTest {
 
         amountSeized = bound(amountSeized, 1, amountCollateral);
 
-        oracle.setPrice(priceCollateral);
+        oracle.setPrice(address(loanToken), address(collateralToken), priceCollateral);
 
         loanToken.setBalance(LIQUIDATOR, amountBorrowed);
         collateralToken.setBalance(BORROWER, amountCollateral);
@@ -94,14 +94,14 @@ contract LiquidateIntegrationTest is BaseTest {
         loanToken.setBalance(LIQUIDATOR, amountBorrowed);
         collateralToken.setBalance(BORROWER, amountCollateral);
 
-        oracle.setPrice(type(uint256).max / amountCollateral);
+        oracle.setPrice(address(loanToken), address(collateralToken), type(uint256).max / amountCollateral);
 
         vm.startPrank(BORROWER);
         morpho.supplyCollateral(marketParams, amountCollateral, BORROWER, hex"");
         morpho.borrow(marketParams, amountBorrowed, 0, BORROWER, BORROWER);
         vm.stopPrank();
 
-        oracle.setPrice(priceCollateral);
+        oracle.setPrice(address(loanToken), address(collateralToken), priceCollateral);
 
         uint256 expectedRepaidShares =
             expectedRepaid.toSharesDown(morpho.totalBorrowAssets(id), morpho.totalBorrowShares(id));
@@ -162,14 +162,14 @@ contract LiquidateIntegrationTest is BaseTest {
         loanToken.setBalance(LIQUIDATOR, amountBorrowed);
         collateralToken.setBalance(BORROWER, amountCollateral);
 
-        oracle.setPrice(type(uint256).max / amountCollateral);
+        oracle.setPrice(address(loanToken), address(collateralToken), type(uint256).max / amountCollateral);
 
         vm.startPrank(BORROWER);
         morpho.supplyCollateral(marketParams, amountCollateral, BORROWER, hex"");
         morpho.borrow(marketParams, amountBorrowed, 0, BORROWER, BORROWER);
         vm.stopPrank();
 
-        oracle.setPrice(priceCollateral);
+        oracle.setPrice(address(loanToken), address(collateralToken), priceCollateral);
 
         vm.prank(LIQUIDATOR);
 
@@ -235,14 +235,14 @@ contract LiquidateIntegrationTest is BaseTest {
         loanToken.setBalance(LIQUIDATOR, amountBorrowed);
         collateralToken.setBalance(BORROWER, amountCollateral);
 
-        oracle.setPrice(type(uint256).max / amountCollateral);
+        oracle.setPrice(address(loanToken), address(collateralToken), type(uint256).max / amountCollateral);
 
         vm.startPrank(BORROWER);
         morpho.supplyCollateral(marketParams, amountCollateral, BORROWER, hex"");
         morpho.borrow(marketParams, amountBorrowed, 0, BORROWER, BORROWER);
         vm.stopPrank();
 
-        oracle.setPrice(priceCollateral);
+        oracle.setPrice(address(loanToken), address(collateralToken), priceCollateral);
 
         params.expectedRepaidShares =
             params.expectedRepaid.toSharesDown(morpho.totalBorrowAssets(id), morpho.totalBorrowShares(id));

test/forge/integration/RepayIntegrationTest.sol

@@ -47,7 +47,7 @@ contract RepayIntegrationTest is BaseTest {
         amountSupplied = bound(amountSupplied, amountBorrowed, MAX_TEST_AMOUNT);
         _supply(amountSupplied);
 
-        oracle.setPrice(priceCollateral);
+        oracle.setPrice(address(loanToken), address(collateralToken), priceCollateral);
 
         amountRepaid = bound(amountRepaid, 1, amountBorrowed);
         uint256 expectedBorrowShares = amountBorrowed.toSharesUp(0, 0);
@@ -90,7 +90,7 @@ contract RepayIntegrationTest is BaseTest {
         amountSupplied = bound(amountSupplied, amountBorrowed, MAX_TEST_AMOUNT);
         _supply(amountSupplied);
 
-        oracle.setPrice(priceCollateral);
+        oracle.setPrice(address(loanToken), address(collateralToken), priceCollateral);
 
         uint256 expectedBorrowShares = amountBorrowed.toSharesUp(0, 0);
         sharesRepaid = bound(sharesRepaid, 1, expectedBorrowShares);

test/forge/integration/WithdrawCollateralIntegrationTest.sol

@@ -68,7 +68,7 @@ contract WithdrawCollateralIntegrationTest is BaseTest {
         amountSupplied = bound(amountSupplied, amountBorrowed, MAX_TEST_AMOUNT);
         _supply(amountSupplied);
 
-        oracle.setPrice(priceCollateral);
+        oracle.setPrice(address(loanToken), address(collateralToken), priceCollateral);
 
         collateralToken.setBalance(BORROWER, amountCollateral);
 
@@ -100,7 +100,7 @@ contract WithdrawCollateralIntegrationTest is BaseTest {
             Math.min(MAX_COLLATERAL_ASSETS - amountCollateral, type(uint256).max / priceCollateral - amountCollateral)
         );
 
-        oracle.setPrice(priceCollateral);
+        oracle.setPrice(address(loanToken), address(collateralToken), priceCollateral);
 
         collateralToken.setBalance(BORROWER, amountCollateral + amountCollateralExcess);
 
@@ -133,7 +133,7 @@ contract WithdrawCollateralIntegrationTest is BaseTest {
         amountSupplied = bound(amountSupplied, amountBorrowed, MAX_TEST_AMOUNT);
         _supply(amountSupplied);
 
-        oracle.setPrice(priceCollateral);
+        oracle.setPrice(address(loanToken), address(collateralToken), priceCollateral);
 
         amountCollateralExcess = bound(
             amountCollateralExcess,

test/forge/invariant/MorphoInvariantTest.sol

@@ -194,7 +194,7 @@ contract MorphoInvariantTest is InvariantTest {
     function setPrice(uint256 price) external {
         price = bound(price, MIN_PRICE, MAX_PRICE);
 
-        oracle.setPrice(price);
+        oracle.setPrice(address(loanToken), address(collateralToken), price);
     }
 
     function setFeeNoRevert(uint256 marketSeed, uint256 newFee) external {