From 8873b9cdacf9cf6f91327af84abb8a25fe751cb7 Mon Sep 17 00:00:00 2001
From: The3D <emilio@aave.com>
Date: Thu, 22 Oct 2020 18:15:56 +0200
Subject: [PATCH 1/5] initial implementation

---
 contracts/interfaces/ILendingPool.sol         |  8 +-
 contracts/lendingpool/LendingPool.sol         | 91 +++++++++++--------
 contracts/libraries/logic/ValidationLogic.sol |  8 +-
 3 files changed, 63 insertions(+), 44 deletions(-)

diff --git a/contracts/interfaces/ILendingPool.sol b/contracts/interfaces/ILendingPool.sol
index 2b4ead37..5271d6bd 100644
--- a/contracts/interfaces/ILendingPool.sol
+++ b/contracts/interfaces/ILendingPool.sol
@@ -270,10 +270,10 @@ interface ILendingPool {
    * @param referralCode the referral code of the caller
    **/
   function flashLoan(
-    address receiver,
-    address reserve,
-    uint256 amount,
-    uint256 debtType,
+    address receiverAddress,
+    address[] calldata assets,
+    uint256[] calldata amounts,
+    uint256 mode,
     bytes calldata params,
     uint16 referralCode
   ) external;
diff --git a/contracts/lendingpool/LendingPool.sol b/contracts/lendingpool/LendingPool.sol
index c1ff20bb..cdf2be48 100644
--- a/contracts/lendingpool/LendingPool.sol
+++ b/contracts/lendingpool/LendingPool.sol
@@ -483,11 +483,9 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
   }
 
   struct FlashLoanLocalVars {
-    uint256 premium;
-    uint256 amountPlusPremium;
     IFlashLoanReceiver receiver;
-    address aTokenAddress;
     address oracle;
+    ReserveLogic.InterestRateMode debtMode;
   }
 
   /**
@@ -495,68 +493,83 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
    * as long as the amount taken plus a fee is returned. NOTE There are security concerns for developers of flashloan receiver contracts
    * that must be kept into consideration. For further details please visit https://developers.aave.com
    * @param receiverAddress The address of the contract receiving the funds. The receiver should implement the IFlashLoanReceiver interface.
-   * @param asset The address of the principal reserve
-   * @param amount The amount requested for this flashloan
+   * @param assets The address of the principal reserve
+   * @param amounts The amount requested for this flashloan
    * @param mode Type of the debt to open if the flash loan is not returned. 0 -> Don't open any debt, just revert, 1 -> stable, 2 -> variable
    * @param params Variadic packed params to pass to the receiver as extra information
    * @param referralCode Referral code of the flash loan
    **/
   function flashLoan(
     address receiverAddress,
-    address asset,
-    uint256 amount,
+    address[] calldata assets,
+    uint256[] calldata amounts,
     uint256 mode,
     bytes calldata params,
     uint16 referralCode
   ) external override {
     _whenNotPaused();
-    ReserveLogic.ReserveData storage reserve = _reserves[asset];
+
     FlashLoanLocalVars memory vars;
 
-    vars.aTokenAddress = reserve.aTokenAddress;
+    ValidationLogic.validateFlashloan(assets, amounts, mode, vars.premium);
 
-    vars.premium = amount.mul(FLASHLOAN_PREMIUM_TOTAL).div(10000);
-
-    ValidationLogic.validateFlashloan(mode, vars.premium);
-
-    ReserveLogic.InterestRateMode debtMode = ReserveLogic.InterestRateMode(mode);
+    address[] memory aTokenAddresses = new address[](assets.length);
+    uint256[] memory premiums = new uint256[](assets.length);
 
     vars.receiver = IFlashLoanReceiver(receiverAddress);
+    vars.debtMode = ReserveLogic.InterestRateMode(mode);
 
-    //transfer funds to the receiver
-    IAToken(vars.aTokenAddress).transferUnderlyingTo(receiverAddress, amount);
+    for (uint256 i = 0; i < assets.length; i++) {
+      ReserveLogic.ReserveData storage reserve = _reserves[assets[i]];
+
+      aTokenAddresses[i] = reserve.aTokenAddress;
+
+      premiums[i] = amounts[i].mul(FLASHLOAN_PREMIUM_TOTAL).div(10000);
+
+      //transfer funds to the receiver
+      IAToken(vars.aTokenAddress).transferUnderlyingTo(receiverAddress, amounts[i]);
+    }
 
     //execute action of the receiver
     require(
-      vars.receiver.executeOperation(asset, amount, vars.premium, params),
+      vars.receiver.executeOperation(assets, amounts, premiums, params),
       Errors.INVALID_FLASH_LOAN_EXECUTOR_RETURN
     );
 
-    vars.amountPlusPremium = amount.add(vars.premium);
+    for (uint256 i = 0; i < assets.length; i++) {
+      uint256 amountPlusPremium = amounts[i].add(premiums[i]);
 
-    if (debtMode == ReserveLogic.InterestRateMode.NONE) {
-      IERC20(asset).safeTransferFrom(receiverAddress, vars.aTokenAddress, vars.amountPlusPremium);
+      if (vars.debtMode == ReserveLogic.InterestRateMode.NONE) {
+        _reserves[assets[i]].updateState();
+        _reserves[assets[i]].cumulateToLiquidityIndex(
+          IERC20(aTokenAddresses[i]).totalSupply(),
+          vars.premium
+        );
+        _reserves[assets[i]].updateInterestRates(assets[i], aTokenAddresses[i], vars.premium, 0);
 
-      reserve.updateState();
-      reserve.cumulateToLiquidityIndex(IERC20(vars.aTokenAddress).totalSupply(), vars.premium);
-      reserve.updateInterestRates(asset, vars.aTokenAddress, vars.premium, 0);
+        IERC20(assets[i]).safeTransferFrom(
+          receiverAddress,
+          vars.aTokenAddresses[i],
+          vars.amountPlusPremium
+        );
 
-      emit FlashLoan(receiverAddress, asset, amount, vars.premium, referralCode);
-    } else {
-      //if the user didn't choose to return the funds, the system checks if there
-      //is enough collateral and eventually open a position
-      _executeBorrow(
-        ExecuteBorrowParams(
-          asset,
-          msg.sender,
-          msg.sender,
-          vars.amountPlusPremium,
-          mode,
-          vars.aTokenAddress,
-          referralCode,
-          false
-        )
-      );
+        emit FlashLoan(receiverAddress, assets[i], amounts[i], vars.premium, referralCode);
+      } else {
+        //if the user didn't choose to return the funds, the system checks if there
+        //is enough collateral and eventually open a position
+        _executeBorrow(
+          ExecuteBorrowParams(
+            assets[i],
+            msg.sender,
+            msg.sender,
+            amountPlusPremium,
+            vars.mode,
+            aTokenAddresses[i],
+            referralCode,
+            false
+          )
+        );
+      }
     }
   }
 
diff --git a/contracts/libraries/logic/ValidationLogic.sol b/contracts/libraries/logic/ValidationLogic.sol
index 93219ce8..838d43b7 100644
--- a/contracts/libraries/logic/ValidationLogic.sol
+++ b/contracts/libraries/logic/ValidationLogic.sol
@@ -329,9 +329,15 @@ library ValidationLogic {
    * @param mode the flashloan mode (0 = classic flashloan, 1 = open a stable rate loan, 2 = open a variable rate loan)
    * @param premium the premium paid on the flashloan
    **/
-  function validateFlashloan(uint256 mode, uint256 premium) internal pure {
+  function validateFlashloan(
+    address[] memory assets,
+    address[] memory amounts,
+    uint256 mode,
+    uint256 premium
+  ) internal pure {
     require(premium > 0, Errors.REQUESTED_AMOUNT_TOO_SMALL);
     require(mode <= uint256(ReserveLogic.InterestRateMode.VARIABLE), Errors.INVALID_FLASHLOAN_MODE);
+    require(assets.length == amounts.length, Errors.INCONSISTENT_FLASHLOAN_PARAMS);
   }
 
   /**

From af99c88b70956eccfec0cea8f16cfe7a6e238d64 Mon Sep 17 00:00:00 2001
From: The3D <emilio@aave.com>
Date: Thu, 22 Oct 2020 19:20:19 +0200
Subject: [PATCH 2/5] Added error constant

---
 contracts/libraries/helpers/Errors.sol | 1 +
 1 file changed, 1 insertion(+)

diff --git a/contracts/libraries/helpers/Errors.sol b/contracts/libraries/helpers/Errors.sol
index ee71efaa..6e13143a 100644
--- a/contracts/libraries/helpers/Errors.sol
+++ b/contracts/libraries/helpers/Errors.sol
@@ -45,6 +45,7 @@ library Errors {
   string public constant INVALID_EQUAL_ASSETS_TO_SWAP = '56';
   string public constant NO_MORE_RESERVES_ALLOWED = '59';
   string public constant INVALID_FLASH_LOAN_EXECUTOR_RETURN = '60';
+  string public constant INCONSISTENT_FLASHLOAN_PARAMS = '69';
 
   // require error messages - aToken - DebtTokens
   string public constant CALLER_MUST_BE_LENDING_POOL = '28'; // 'The caller of this function must be a lending pool'

From a2e2450bb351844086f749ee24c005df03bc0e4a Mon Sep 17 00:00:00 2001
From: The3D <emilio@aave.com>
Date: Thu, 22 Oct 2020 20:37:50 +0200
Subject: [PATCH 3/5] Finalized implementation, fixed tests

---
 .../interfaces/IFlashLoanReceiver.sol         |  6 +-
 contracts/interfaces/ILendingPool.sol         | 19 +++---
 contracts/lendingpool/LendingPool.sol         | 59 ++++++++++-------
 contracts/libraries/logic/ValidationLogic.sol |  9 ++-
 .../mocks/flashloan/MockFlashLoanReceiver.sol | 43 +++++++------
 test/flashloan.spec.ts                        | 64 ++++++++-----------
 test/pausable-functions.spec.ts               |  2 +-
 7 files changed, 107 insertions(+), 95 deletions(-)

diff --git a/contracts/flashloan/interfaces/IFlashLoanReceiver.sol b/contracts/flashloan/interfaces/IFlashLoanReceiver.sol
index 5c92236a..8d4353f3 100644
--- a/contracts/flashloan/interfaces/IFlashLoanReceiver.sol
+++ b/contracts/flashloan/interfaces/IFlashLoanReceiver.sol
@@ -9,9 +9,9 @@ pragma solidity ^0.6.8;
  **/
 interface IFlashLoanReceiver {
   function executeOperation(
-    address reserve,
-    uint256 amount,
-    uint256 fee,
+    address[] calldata reserve,
+    uint256[] calldata amounts,
+    uint256[] calldata premiums,
     bytes calldata params
   ) external returns (bool);
 }
diff --git a/contracts/interfaces/ILendingPool.sol b/contracts/interfaces/ILendingPool.sol
index 5271d6bd..4e36c87b 100644
--- a/contracts/interfaces/ILendingPool.sol
+++ b/contracts/interfaces/ILendingPool.sol
@@ -99,16 +99,16 @@ interface ILendingPool {
   /**
    * @dev emitted when a flashloan is executed
    * @param target the address of the flashLoanReceiver
-   * @param reserve the address of the reserve
-   * @param amount the amount requested
-   * @param totalPremium the total fee on the amount
+   * @param assets the address of the assets being flashborrowed
+   * @param amounts the amount requested
+   * @param premiums the total fee on the amount
    * @param referralCode the referral code of the caller
    **/
   event FlashLoan(
     address indexed target,
-    address indexed reserve,
-    uint256 amount,
-    uint256 totalPremium,
+    address[] assets,
+    uint256[] amounts,
+    uint256[] premiums,
     uint16 referralCode
   );
   /**
@@ -264,13 +264,14 @@ interface ILendingPool {
    * as long as the amount taken plus a fee is returned. NOTE There are security concerns for developers of flashloan receiver contracts
    * that must be kept into consideration. For further details please visit https://developers.aave.com
    * @param receiver The address of the contract receiving the funds. The receiver should implement the IFlashLoanReceiver interface.
-   * @param reserve the address of the principal reserve
-   * @param amount the amount requested for this flashloan
+   * @param assets the address of the principal reserve
+   * @param amounts the amount requested for this flashloan
+   * @param mode the flashloan mode
    * @param params a bytes array to be sent to the flashloan executor
    * @param referralCode the referral code of the caller
    **/
   function flashLoan(
-    address receiverAddress,
+    address receiver,
     address[] calldata assets,
     uint256[] calldata amounts,
     uint256 mode,
diff --git a/contracts/lendingpool/LendingPool.sol b/contracts/lendingpool/LendingPool.sol
index cdf2be48..fc9413ab 100644
--- a/contracts/lendingpool/LendingPool.sol
+++ b/contracts/lendingpool/LendingPool.sol
@@ -486,6 +486,12 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
     IFlashLoanReceiver receiver;
     address oracle;
     ReserveLogic.InterestRateMode debtMode;
+    uint256 i;
+    address currentAsset;
+    address currentATokenAddress;
+    uint256 currentAmount;
+    uint256 currentPremium;
+    uint256 currentAmountPlusPremium;
   }
 
   /**
@@ -511,7 +517,7 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
 
     FlashLoanLocalVars memory vars;
 
-    ValidationLogic.validateFlashloan(assets, amounts, mode, vars.premium);
+    ValidationLogic.validateFlashloan(assets, amounts, mode);
 
     address[] memory aTokenAddresses = new address[](assets.length);
     uint256[] memory premiums = new uint256[](assets.length);
@@ -519,15 +525,13 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
     vars.receiver = IFlashLoanReceiver(receiverAddress);
     vars.debtMode = ReserveLogic.InterestRateMode(mode);
 
-    for (uint256 i = 0; i < assets.length; i++) {
-      ReserveLogic.ReserveData storage reserve = _reserves[assets[i]];
+    for (vars.i = 0; vars.i < assets.length; vars.i++) {
+      aTokenAddresses[vars.i] = _reserves[assets[vars.i]].aTokenAddress;
 
-      aTokenAddresses[i] = reserve.aTokenAddress;
-
-      premiums[i] = amounts[i].mul(FLASHLOAN_PREMIUM_TOTAL).div(10000);
+      premiums[vars.i] = amounts[vars.i].mul(FLASHLOAN_PREMIUM_TOTAL).div(10000);
 
       //transfer funds to the receiver
-      IAToken(vars.aTokenAddress).transferUnderlyingTo(receiverAddress, amounts[i]);
+      IAToken(aTokenAddresses[vars.i]).transferUnderlyingTo(receiverAddress, amounts[vars.i]);
     }
 
     //execute action of the receiver
@@ -536,40 +540,49 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
       Errors.INVALID_FLASH_LOAN_EXECUTOR_RETURN
     );
 
-    for (uint256 i = 0; i < assets.length; i++) {
-      uint256 amountPlusPremium = amounts[i].add(premiums[i]);
+    for (vars.i = 0; vars.i < assets.length; vars.i++) {
+      vars.currentAsset = assets[vars.i];
+      vars.currentAmount = amounts[vars.i];
+      vars.currentPremium = premiums[vars.i];
+      vars.currentATokenAddress = aTokenAddresses[vars.i];
+
+      vars.currentAmountPlusPremium = amounts[vars.i].add(premiums[vars.i]);
 
       if (vars.debtMode == ReserveLogic.InterestRateMode.NONE) {
-        _reserves[assets[i]].updateState();
-        _reserves[assets[i]].cumulateToLiquidityIndex(
-          IERC20(aTokenAddresses[i]).totalSupply(),
-          vars.premium
+        _reserves[vars.currentAsset].updateState();
+        _reserves[vars.currentAsset].cumulateToLiquidityIndex(
+          IERC20(vars.currentATokenAddress).totalSupply(),
+          vars.currentPremium
+        );
+        _reserves[vars.currentAsset].updateInterestRates(
+          assets[vars.i],
+          vars.currentATokenAddress,
+          vars.currentPremium,
+          0
         );
-        _reserves[assets[i]].updateInterestRates(assets[i], aTokenAddresses[i], vars.premium, 0);
 
-        IERC20(assets[i]).safeTransferFrom(
+        IERC20(vars.currentAsset).safeTransferFrom(
           receiverAddress,
-          vars.aTokenAddresses[i],
-          vars.amountPlusPremium
+          vars.currentATokenAddress,
+          vars.currentAmountPlusPremium
         );
-
-        emit FlashLoan(receiverAddress, assets[i], amounts[i], vars.premium, referralCode);
       } else {
         //if the user didn't choose to return the funds, the system checks if there
         //is enough collateral and eventually open a position
         _executeBorrow(
           ExecuteBorrowParams(
-            assets[i],
+            vars.currentAsset,
             msg.sender,
             msg.sender,
-            amountPlusPremium,
-            vars.mode,
-            aTokenAddresses[i],
+            vars.currentAmount,
+            mode,
+            vars.currentATokenAddress,
             referralCode,
             false
           )
         );
       }
+      emit FlashLoan(receiverAddress, assets, amounts, premiums, referralCode);
     }
   }
 
diff --git a/contracts/libraries/logic/ValidationLogic.sol b/contracts/libraries/logic/ValidationLogic.sol
index 838d43b7..947d84ea 100644
--- a/contracts/libraries/logic/ValidationLogic.sol
+++ b/contracts/libraries/logic/ValidationLogic.sol
@@ -327,15 +327,14 @@ library ValidationLogic {
   /**
    * @dev validates a flashloan action
    * @param mode the flashloan mode (0 = classic flashloan, 1 = open a stable rate loan, 2 = open a variable rate loan)
-   * @param premium the premium paid on the flashloan
+   * @param assets the assets being flashborrowed
+   * @param amounts the amounts for each asset being borrowed
    **/
   function validateFlashloan(
     address[] memory assets,
-    address[] memory amounts,
-    uint256 mode,
-    uint256 premium
+    uint256[] memory amounts,
+    uint256 mode
   ) internal pure {
-    require(premium > 0, Errors.REQUESTED_AMOUNT_TOO_SMALL);
     require(mode <= uint256(ReserveLogic.InterestRateMode.VARIABLE), Errors.INVALID_FLASHLOAN_MODE);
     require(assets.length == amounts.length, Errors.INCONSISTENT_FLASHLOAN_PARAMS);
   }
diff --git a/contracts/mocks/flashloan/MockFlashLoanReceiver.sol b/contracts/mocks/flashloan/MockFlashLoanReceiver.sol
index 0a767712..7b72c2cb 100644
--- a/contracts/mocks/flashloan/MockFlashLoanReceiver.sol
+++ b/contracts/mocks/flashloan/MockFlashLoanReceiver.sol
@@ -14,8 +14,8 @@ contract MockFlashLoanReceiver is FlashLoanReceiverBase {
 
   ILendingPoolAddressesProvider internal _provider;
 
-  event ExecutedWithFail(address _reserve, uint256 _amount, uint256 _fee);
-  event ExecutedWithSuccess(address _reserve, uint256 _amount, uint256 _fee);
+  event ExecutedWithFail(address[] _assets, uint256[] _amounts, uint256[] _premiums);
+  event ExecutedWithSuccess(address[] _assets, uint256[] _amounts, uint256[] _premiums);
 
   bool _failExecution;
   uint256 _amountToApprove;
@@ -44,33 +44,40 @@ contract MockFlashLoanReceiver is FlashLoanReceiverBase {
   }
 
   function executeOperation(
-    address reserve,
-    uint256 amount,
-    uint256 fee,
+    address[] memory assets,
+    uint256[] memory amounts,
+    uint256[] memory premiums,
     bytes memory params
   ) public override returns (bool) {
     params;
-    //mint to this contract the specific amount
-    MintableERC20 token = MintableERC20(reserve);
-
-    //check the contract has the specified balance
-    require(amount <= IERC20(reserve).balanceOf(address(this)), 'Invalid balance for the contract');
-
-    uint256 amountToReturn = (_amountToApprove != 0) ? _amountToApprove : amount.add(fee);
 
     if (_failExecution) {
-      emit ExecutedWithFail(reserve, amount, fee);
+      emit ExecutedWithFail(assets, amounts, premiums);
       return !_simulateEOA;
     }
 
-    //execution does not fail - mint tokens and return them to the _destination
-    //note: if the reserve is eth, the mock contract must receive at least _fee ETH before calling executeOperation
+    for (uint256 i = 0; i < assets.length; i++) {
+      //mint to this contract the specific amount
+      MintableERC20 token = MintableERC20(assets[i]);
 
-    token.mint(fee);
+      //check the contract has the specified balance
+      require(
+        amounts[i] <= IERC20(assets[i]).balanceOf(address(this)),
+        'Invalid balance for the contract'
+      );
 
-    IERC20(reserve).approve(_addressesProvider.getLendingPool(), amountToReturn);
+      uint256 amountToReturn = (_amountToApprove != 0)
+        ? _amountToApprove
+        : amounts[i].add(premiums[i]);
+      //execution does not fail - mint tokens and return them to the _destination
+      //note: if the reserve is eth, the mock contract must receive at least _fee ETH before calling executeOperation
 
-    emit ExecutedWithSuccess(reserve, amount, fee);
+      token.mint(premiums[i]);
+
+      IERC20(assets[i]).approve(_addressesProvider.getLendingPool(), amountToReturn);
+    }
+
+    emit ExecutedWithSuccess(assets, amounts, premiums);
 
     return true;
   }
diff --git a/test/flashloan.spec.ts b/test/flashloan.spec.ts
index 1ca080f9..c34c37b1 100644
--- a/test/flashloan.spec.ts
+++ b/test/flashloan.spec.ts
@@ -48,8 +48,8 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
 
     await pool.flashLoan(
       _mockFlashLoanReceiver.address,
-      weth.address,
-      ethers.utils.parseEther('0.8'),
+      [weth.address],
+      [ethers.utils.parseEther('0.8')],
       0,
       '0x10',
       '0'
@@ -77,8 +77,8 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
     const reserveDataBefore = await helpersContract.getReserveData(weth.address);
     const txResult = await pool.flashLoan(
       _mockFlashLoanReceiver.address,
-      weth.address,
-      '1000720000000000000',
+      [weth.address],
+      ['1000720000000000000'],
       0,
       '0x10',
       '0'
@@ -108,8 +108,8 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
         .connect(caller.signer)
         .flashLoan(
           _mockFlashLoanReceiver.address,
-          weth.address,
-          ethers.utils.parseEther('0.8'),
+          [weth.address],
+          [ethers.utils.parseEther('0.8')],
           0,
           '0x10',
           '0'
@@ -128,8 +128,8 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
         .connect(caller.signer)
         .flashLoan(
           _mockFlashLoanReceiver.address,
-          weth.address,
-          ethers.utils.parseEther('0.8'),
+          [weth.address],
+          [ethers.utils.parseEther('0.8')],
           0,
           '0x10',
           '0'
@@ -148,8 +148,8 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
         .connect(caller.signer)
         .flashLoan(
           _mockFlashLoanReceiver.address,
-          weth.address,
-          ethers.utils.parseEther('0.8'),
+          [weth.address],
+          [ethers.utils.parseEther('0.8')],
           4,
           '0x10',
           '0'
@@ -176,8 +176,8 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
       .connect(caller.signer)
       .flashLoan(
         _mockFlashLoanReceiver.address,
-        weth.address,
-        ethers.utils.parseEther('0.8'),
+        [weth.address],
+        [ethers.utils.parseEther('0.8')],
         2,
         '0x10',
         '0'
@@ -196,29 +196,14 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
     expect(callerDebt.toString()).to.be.equal('800720000000000000', 'Invalid user debt');
   });
 
-  it('tries to take a very small flashloan, which would result in 0 fees (revert expected)', async () => {
-    const {pool, weth} = testEnv;
-
-    await expect(
-      pool.flashLoan(
-        _mockFlashLoanReceiver.address,
-        weth.address,
-        '1', //1 wei loan
-        2,
-        '0x10',
-        '0'
-      )
-    ).to.be.revertedWith(REQUESTED_AMOUNT_TOO_SMALL);
-  });
-
   it('tries to take a flashloan that is bigger than the available liquidity (revert expected)', async () => {
     const {pool, weth} = testEnv;
 
     await expect(
       pool.flashLoan(
         _mockFlashLoanReceiver.address,
-        weth.address,
-        '1004415000000000000', //slightly higher than the available liquidity
+        [weth.address],
+        ['1004415000000000000'], //slightly higher than the available liquidity
         2,
         '0x10',
         '0'
@@ -231,7 +216,7 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
     const {pool, deployer, weth} = testEnv;
 
     await expect(
-      pool.flashLoan(deployer.address, weth.address, '1000000000000000000', 2, '0x10', '0')
+      pool.flashLoan(deployer.address, [weth.address], ['1000000000000000000'], 2, '0x10', '0')
     ).to.be.reverted;
   });
 
@@ -257,8 +242,8 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
 
     await pool.flashLoan(
       _mockFlashLoanReceiver.address,
-      usdc.address,
-      flashloanAmount,
+      [usdc.address],
+      [flashloanAmount],
       0,
       '0x10',
       '0'
@@ -297,7 +282,14 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
     await expect(
       pool
         .connect(caller.signer)
-        .flashLoan(_mockFlashLoanReceiver.address, usdc.address, flashloanAmount, 2, '0x10', '0')
+        .flashLoan(
+          _mockFlashLoanReceiver.address,
+          [usdc.address],
+          [flashloanAmount],
+          2,
+          '0x10',
+          '0'
+        )
     ).to.be.revertedWith(COLLATERAL_BALANCE_IS_0);
   });
 
@@ -320,7 +312,7 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
 
     await pool
       .connect(caller.signer)
-      .flashLoan(_mockFlashLoanReceiver.address, usdc.address, flashloanAmount, 2, '0x10', '0');
+      .flashLoan(_mockFlashLoanReceiver.address, [usdc.address], [flashloanAmount], 2, '0x10', '0');
     const {variableDebtTokenAddress} = await helpersContract.getReserveTokensAddresses(
       usdc.address
     );
@@ -355,7 +347,7 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
     await expect(
       pool
         .connect(caller.signer)
-        .flashLoan(_mockFlashLoanReceiver.address, weth.address, flashAmount, 0, '0x10', '0')
+        .flashLoan(_mockFlashLoanReceiver.address, [weth.address], [flashAmount], 0, '0x10', '0')
     ).to.be.revertedWith(SAFEERC20_LOWLEVEL_CALL);
   });
 
@@ -370,7 +362,7 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
 
     await pool
       .connect(caller.signer)
-      .flashLoan(_mockFlashLoanReceiver.address, weth.address, flashAmount, 1, '0x10', '0');
+      .flashLoan(_mockFlashLoanReceiver.address, [weth.address], [flashAmount], 1, '0x10', '0');
 
     const {stableDebtTokenAddress} = await helpersContract.getReserveTokensAddresses(weth.address);
 
diff --git a/test/pausable-functions.spec.ts b/test/pausable-functions.spec.ts
index 8e7cc2a7..cc8fb0d4 100644
--- a/test/pausable-functions.spec.ts
+++ b/test/pausable-functions.spec.ts
@@ -186,7 +186,7 @@ makeSuite('Pausable Pool', (testEnv: TestEnv) => {
     await expect(
       pool
         .connect(caller.signer)
-        .flashLoan(_mockFlashLoanReceiver.address, weth.address, flashAmount, 1, '0x10', '0')
+        .flashLoan(_mockFlashLoanReceiver.address, [weth.address], [flashAmount], 1, '0x10', '0')
     ).revertedWith(IS_PAUSED);
 
     // Unpause pool

From 6398fe4260a10beff1dd299fb539e11f54ca71ff Mon Sep 17 00:00:00 2001
From: The3D <emilio@aave.com>
Date: Fri, 23 Oct 2020 18:41:08 +0200
Subject: [PATCH 4/5] Fix comments, tests

---
 contracts/flashloan/interfaces/IFlashLoanReceiver.sol | 2 +-
 contracts/lendingpool/LendingPool.sol                 | 8 ++++----
 test/flashloan.spec.ts                                | 6 +++---
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/contracts/flashloan/interfaces/IFlashLoanReceiver.sol b/contracts/flashloan/interfaces/IFlashLoanReceiver.sol
index 8d4353f3..784d0fa3 100644
--- a/contracts/flashloan/interfaces/IFlashLoanReceiver.sol
+++ b/contracts/flashloan/interfaces/IFlashLoanReceiver.sol
@@ -9,7 +9,7 @@ pragma solidity ^0.6.8;
  **/
 interface IFlashLoanReceiver {
   function executeOperation(
-    address[] calldata reserve,
+    address[] calldata assets,
     uint256[] calldata amounts,
     uint256[] calldata premiums,
     bytes calldata params
diff --git a/contracts/lendingpool/LendingPool.sol b/contracts/lendingpool/LendingPool.sol
index fc9413ab..a16e9cd6 100644
--- a/contracts/lendingpool/LendingPool.sol
+++ b/contracts/lendingpool/LendingPool.sol
@@ -499,8 +499,8 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
    * as long as the amount taken plus a fee is returned. NOTE There are security concerns for developers of flashloan receiver contracts
    * that must be kept into consideration. For further details please visit https://developers.aave.com
    * @param receiverAddress The address of the contract receiving the funds. The receiver should implement the IFlashLoanReceiver interface.
-   * @param assets The address of the principal reserve
-   * @param amounts The amount requested for this flashloan
+   * @param assets The addresss of the assets being flashborrowed
+   * @param amounts The amounts requested for this flashloan for each asset
    * @param mode Type of the debt to open if the flash loan is not returned. 0 -> Don't open any debt, just revert, 1 -> stable, 2 -> variable
    * @param params Variadic packed params to pass to the receiver as extra information
    * @param referralCode Referral code of the flash loan
@@ -546,7 +546,7 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
       vars.currentPremium = premiums[vars.i];
       vars.currentATokenAddress = aTokenAddresses[vars.i];
 
-      vars.currentAmountPlusPremium = amounts[vars.i].add(premiums[vars.i]);
+      vars.currentAmountPlusPremium = vars.currentAmount.add(vars.currentPremium);
 
       if (vars.debtMode == ReserveLogic.InterestRateMode.NONE) {
         _reserves[vars.currentAsset].updateState();
@@ -555,7 +555,7 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
           vars.currentPremium
         );
         _reserves[vars.currentAsset].updateInterestRates(
-          assets[vars.i],
+          vars.currentAsset,
           vars.currentATokenAddress,
           vars.currentPremium,
           0
diff --git a/test/flashloan.spec.ts b/test/flashloan.spec.ts
index c34c37b1..4edd4848 100644
--- a/test/flashloan.spec.ts
+++ b/test/flashloan.spec.ts
@@ -193,7 +193,7 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
 
     const callerDebt = await wethDebtToken.balanceOf(caller.address);
 
-    expect(callerDebt.toString()).to.be.equal('800720000000000000', 'Invalid user debt');
+    expect(callerDebt.toString()).to.be.equal('800000000000000000', 'Invalid user debt');
   });
 
   it('tries to take a flashloan that is bigger than the available liquidity (revert expected)', async () => {
@@ -324,7 +324,7 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
 
     const callerDebt = await usdcDebtToken.balanceOf(caller.address);
 
-    expect(callerDebt.toString()).to.be.equal('500450000', 'Invalid user debt');
+    expect(callerDebt.toString()).to.be.equal('500000000', 'Invalid user debt');
   });
 
   it('Caller deposits 1000 DAI as collateral, Takes a WETH flashloan with mode = 0, does not approve the transfer of the funds', async () => {
@@ -373,6 +373,6 @@ makeSuite('LendingPool FlashLoan function', (testEnv: TestEnv) => {
 
     const callerDebt = await wethDebtToken.balanceOf(caller.address);
 
-    expect(callerDebt.toString()).to.be.equal('800720000000000000', 'Invalid user debt');
+    expect(callerDebt.toString()).to.be.equal('800000000000000000', 'Invalid user debt');
   });
 });

From c44ed2c0c7c54535456b7c88176efeeda97dce3e Mon Sep 17 00:00:00 2001
From: The3D <emilio@aave.com>
Date: Mon, 26 Oct 2020 10:35:44 +0100
Subject: [PATCH 5/5] Updated flashloan event

---
 contracts/interfaces/ILendingPool.sol | 1 +
 contracts/lendingpool/LendingPool.sol | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/contracts/interfaces/ILendingPool.sol b/contracts/interfaces/ILendingPool.sol
index 4e36c87b..891781dc 100644
--- a/contracts/interfaces/ILendingPool.sol
+++ b/contracts/interfaces/ILendingPool.sol
@@ -106,6 +106,7 @@ interface ILendingPool {
    **/
   event FlashLoan(
     address indexed target,
+    uint256 mode,
     address[] assets,
     uint256[] amounts,
     uint256[] premiums,
diff --git a/contracts/lendingpool/LendingPool.sol b/contracts/lendingpool/LendingPool.sol
index a16e9cd6..22dd7454 100644
--- a/contracts/lendingpool/LendingPool.sol
+++ b/contracts/lendingpool/LendingPool.sol
@@ -582,7 +582,7 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
           )
         );
       }
-      emit FlashLoan(receiverAddress, assets, amounts, premiums, referralCode);
+      emit FlashLoan(receiverAddress, mode, assets, amounts, premiums, referralCode);
     }
   }