Merge branch 'fix/50-check-on-balancedecreaseallowed' into 'master'

Resolve "Fix: Check on balanceDecreaseAllowed() if the reserve liquidation threshold is 0, not the ltv"

Closes #50

See merge request aave-tech/protocol-v2!59

contracts/libraries/logic/GenericLogic.sol

@@ -29,11 +29,10 @@ library GenericLogic {
 
   struct balanceDecreaseAllowedLocalVars {
     uint256 decimals;
-    uint256 ltv;
+    uint256 liquidationThreshold;
     uint256 collateralBalanceETH;
     uint256 borrowBalanceETH;
-    uint256 currentLiquidationThreshold;
+    uint256 avgLiquidationThreshold;
-    uint256 reserveLiquidationThreshold;
     uint256 amountToDecreaseETH;
     uint256 collateralBalancefterDecrease;
     uint256 liquidationThresholdAfterDecrease;
@@ -62,18 +61,15 @@ library GenericLogic {
     address[] calldata reserves,
     address oracle
   ) external view returns (bool) {
-    if (
+    if (!userConfig.isBorrowingAny() || !userConfig.isUsingAsCollateral(reservesData[asset].id)) {
-      !userConfig.isBorrowingAny() ||
-      !userConfig.isUsingAsCollateral(reservesData[asset].id)
-    ) {
       return true;
     }
 
     balanceDecreaseAllowedLocalVars memory vars;
 
-    (vars.ltv, , , vars.decimals) = reservesData[asset].configuration.getParams();
+    (, vars.liquidationThreshold, , vars.decimals) = reservesData[asset].configuration.getParams();
 
-    if (vars.ltv == 0) {
+    if (vars.liquidationThreshold == 0) {
       return true; //if reserve is not used as collateral, no reasons to block the transfer
     }
 
@@ -81,7 +77,7 @@ library GenericLogic {
       vars.collateralBalanceETH,
       vars.borrowBalanceETH,
       ,
-      vars.currentLiquidationThreshold,
+      vars.avgLiquidationThreshold,
 
     ) = calculateUserAccountData(user, reservesData, userConfig, reserves, oracle);
 
@@ -102,8 +98,8 @@ library GenericLogic {
 
     vars.liquidationThresholdAfterDecrease = vars
       .collateralBalanceETH
-      .mul(vars.currentLiquidationThreshold)
+      .mul(vars.avgLiquidationThreshold)
-      .sub(vars.amountToDecreaseETH.mul(vars.reserveLiquidationThreshold))
+      .sub(vars.amountToDecreaseETH.mul(vars.liquidationThreshold))
       .div(vars.collateralBalancefterDecrease);
 
     uint256 healthFactorAfterDecrease = calculateHealthFactorFromBalances(
@@ -186,7 +182,7 @@ library GenericLogic {
       vars.tokenUnit = 10**vars.decimals;
       vars.reserveUnitPrice = IPriceOracleGetter(oracle).getAssetPrice(vars.currentReserveAddress);
 
-      if (vars.ltv != 0 && userConfig.isUsingAsCollateral(vars.i)) {
+      if (vars.liquidationThreshold != 0 && userConfig.isUsingAsCollateral(vars.i)) {
         vars.compoundedLiquidityBalance = IERC20(currentReserve.aTokenAddress).balanceOf(user);
 
         uint256 liquidityBalanceETH = vars
@@ -254,7 +250,7 @@ library GenericLogic {
     return (collateralBalanceETH.percentMul(liquidationThreshold)).wadDiv(borrowBalanceETH);
   }
 
-    /**
+  /**
    * @dev calculates the equivalent amount in ETH that an user can borrow, depending on the available collateral and the
    * average Loan To Value.
    * @param collateralBalanceETH the total collateral balance

test/flash-liquidation-with-collateral.spec.ts

@@ -833,12 +833,13 @@ makeSuite('LendingPool. repayWithCollateral() with liquidator', (testEnv: TestEn
     await oracle.setAssetPrice(dai.address, daiPrice);
   });
 
-  it('User 5 deposits WETH and DAI, then borrows USDC at Variable, then disables WETH as collateral', async () => {
+  it('User 4 deposits WETH, LEND and DAI, then borrows USDC at Variable, then disables WETH as collateral', async () => {
     const {pool, weth, dai, usdc, users} = testEnv;
     const user = users[4];
     const amountWETHToDeposit = parseEther('10');
-    const amountDAIToDeposit = parseEther('60');
+    const amountDAIToDeposit = parseEther('100');
-    const amountToBorrow = parseUnits('65', 6);
+
+    const amountToBorrow = parseUnits('75', 6);
 
     await weth.connect(user.signer).mint(amountWETHToDeposit);
     await weth.connect(user.signer).approve(pool.address, APPROVAL_AMOUNT_LENDING_POOL);
@@ -851,8 +852,8 @@ makeSuite('LendingPool. repayWithCollateral() with liquidator', (testEnv: TestEn
     await pool.connect(user.signer).borrow(usdc.address, amountToBorrow, 2, 0, user.address);
   });
 
-  it('Liquidator tries to liquidates User 5 USDC loan by swapping his WETH collateral, should revert due WETH collateral disabled', async () => {
+  it('Liquidator tries to liquidate User 5 USDC loan by swapping his WETH collateral, should revert due WETH collateral disabled', async () => {
-    const {pool, weth, usdc, users, mockSwapAdapter, oracle} = testEnv;
+    const {pool, weth, dai, usdc, users, mockSwapAdapter, oracle} = testEnv;
     const user = users[4];
     const liquidator = users[5];
 
@@ -874,6 +875,14 @@ makeSuite('LendingPool. repayWithCollateral() with liquidator', (testEnv: TestEn
 
     expect(wethUserDataBefore.usageAsCollateralEnabled).to.be.false;
 
+    //drop the price to set the HF below 1
+    const daiPrice = await oracle.getAssetPrice(dai.address);
+
+    await oracle.setAssetPrice(
+          dai.address,
+          new BigNumber(daiPrice.toString()).multipliedBy(0.9).toFixed(0)
+        );
+    
     // Liquidator should NOT be able to liquidate himself with WETH, even if is disabled
     await mockSwapAdapter.setAmountToReturn(amountToRepay);
     await expect(
@@ -888,6 +897,7 @@ makeSuite('LendingPool. repayWithCollateral() with liquidator', (testEnv: TestEn
           '0x'
         )
     ).to.be.revertedWith(COLLATERAL_CANNOT_BE_LIQUIDATED);
+
     const repayWithCollateralTimestamp = await timeLatest();
 
     const {userData: wethUserDataAfter} = await getContractsData(

test/helpers/scenarios/set-use-as-collateral.json

@@ -43,7 +43,7 @@
       ]
     },
     {
-      "description": "User 1 Deposits 2 ETH, disables ETH as collateral, borrows 400 DAI (revert expected)",
+      "description": "User 1 Deposits 2 WETH, disables WETH as collateral, borrows 400 DAI (revert expected)",
       "actions": [
         {
           "name": "mint",
@@ -96,7 +96,7 @@
       ]
     },
     {
-      "description": "User 1 enables ETH as collateral, borrows 400 DAI",
+      "description": "User 1 enables WETH as collateral, borrows 400 DAI",
       "actions": [
         {
           "name": "setUseAsCollateral",
@@ -120,7 +120,7 @@
       ]
     },
     {
-      "description": "User 1 disables ETH as collateral (revert expected)",
+      "description": "User 1 disables WETH as collateral (revert expected)",
       "actions": [
         {
           "name": "setUseAsCollateral",
@@ -134,6 +134,97 @@
           "revertMessage": "User deposit is already being used as collateral"
         }
       ]
+    },
+    {
+      "description": "User 1 Deposits 1000 LEND, disables WETH as collateral. Should revert as 1000 LEND are not enough to cover the debt (revert expected)",
+      "actions": [
+        {
+          "name": "mint",
+          "args": {
+            "reserve": "LEND",
+            "amount": "1000",
+            "user": "1"
+          },
+          "expected": "success"
+        },
+        {
+          "name": "approve",
+          "args": {
+            "reserve": "LEND",
+            "user": "1"
+          },
+          "expected": "success"
+        },
+        {
+          "name": "deposit",
+          "args": {
+            "reserve": "LEND",
+
+            "amount": "1000",
+            "user": "1"
+          },
+          "expected": "success"
+        },
+        {
+          "name": "setUseAsCollateral",
+          "args": {
+            "reserve": "WETH",
+
+            "user": "1",
+            "useAsCollateral": "false"
+          },
+          "expected": "revert"
+        }
+      ]
+    },
+    {
+      "description": "User 1 Deposits 64000 more LEND (enough to cover the DAI debt), disables WETH as collateral",
+      "actions": [
+        {
+          "name": "mint",
+          "args": {
+            "reserve": "LEND",
+            "amount": "64000",
+            "user": "1"
+          },
+          "expected": "success"
+        },
+        {
+          "name": "deposit",
+          "args": {
+            "reserve": "LEND",
+
+            "amount": "64000",
+            "user": "1"
+          },
+          "expected": "success"
+        },
+        {
+          "name": "setUseAsCollateral",
+          "args": {
+            "reserve": "WETH",
+
+            "user": "1",
+            "useAsCollateral": "false"
+          },
+          "expected": "success"
+        }
+      ]
+    },
+    {
+      "description": "User 1 disables LEND as collateral (revert expected)",
+      "actions": [
+        {
+          "name": "setUseAsCollateral",
+          "args": {
+            "reserve": "LEND",
+
+            "user": "1",
+            "useAsCollateral": "false"
+          },
+          "expected": "User deposit is already being used as collateral"
+        }
+      ]
     }
   ]
 }