Merge pull request #172 from aave/fix/protocol-2.5-withdraw-exposure-capped

Fix/protocol 2.5 withdraw exposure capped

contracts/protocol/lendingpool/LendingPool.sol

@@ -282,7 +282,9 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
     DataTypes.ReserveData storage reserve = _reserves[asset];
     DataTypes.ReserveCache memory reserveCache = reserve.cache();
 
-    ValidationLogic.validateSetUseReserveAsCollateral(reserveCache);
+    uint256 userBalance = IERC20(reserveCache.aTokenAddress).balanceOf(msg.sender);
+
+    ValidationLogic.validateSetUseReserveAsCollateral(reserveCache, userBalance);
 
     _usersConfig[msg.sender].setUsingAsCollateral(reserve.id, useAsCollateral);
 
@@ -291,6 +293,7 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
     } else {
       ValidationLogic.validateHFAndExposureCap(
         asset,
+        userBalance,
         msg.sender,
         _reserves,
         _usersConfig[msg.sender],
@@ -498,6 +501,7 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
       ltv,
       currentLiquidationThreshold,
       healthFactor,
+
     ) = GenericLogic.getUserAccountData(
       user,
       _reserves,
@@ -631,6 +635,7 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
         if (fromConfig.isBorrowingAny()) {
           ValidationLogic.validateHFAndExposureCap(
             asset,
+            amount,
             from,
             _reserves,
             _usersConfig[from],
@@ -879,6 +884,7 @@ contract LendingPool is VersionedInitializable, ILendingPool, LendingPoolStorage
       if (userConfig.isBorrowingAny()) {
         ValidationLogic.validateHFAndExposureCap(
           asset,
+          0,
           msg.sender,
           _reserves,
           userConfig,

contracts/protocol/libraries/logic/ValidationLogic.sol

@@ -186,6 +186,7 @@ library ValidationLogic {
       vars.currentLtv,
       vars.currentLiquidationThreshold,
       vars.healthFactor,
+
     ) = GenericLogic.calculateUserAccountData(
       userAddress,
       reservesData,
@@ -387,17 +388,16 @@ library ValidationLogic {
    * @dev Validates the action of setting an asset as collateral
    * @param reserveCache The cached data of the reserve
    */
-  function validateSetUseReserveAsCollateral(DataTypes.ReserveCache memory reserveCache)
+  function validateSetUseReserveAsCollateral(
-    external
+    DataTypes.ReserveCache memory reserveCache,
-    view
+    uint256 userBalance
-  {
+  ) external pure {
-    uint256 underlyingBalance = IERC20(reserveCache.aTokenAddress).balanceOf(msg.sender);
     (bool isActive, , , , bool isPaused) = reserveCache.reserveConfiguration.getFlagsMemory();
 
     require(isActive, Errors.VL_NO_ACTIVE_RESERVE);
     require(!isPaused, Errors.VL_RESERVE_PAUSED);
 
-    require(underlyingBalance > 0, Errors.VL_UNDERLYING_BALANCE_NOT_GREATER_THAN_0);
+    require(userBalance > 0, Errors.VL_UNDERLYING_BALANCE_NOT_GREATER_THAN_0);
   }
 
   /**
@@ -507,8 +507,19 @@ library ValidationLogic {
     return (uint256(Errors.CollateralManagerErrors.NO_ERROR), Errors.LPCM_NO_ERRORS);
   }
 
+  struct validateHFAndExposureCapLocalVars {
+    uint256 healthFactor;
+    uint256 ltv;
+    uint256 uncappedLtv;
+    uint256 exposureCap;
+    uint256 reserveDecimals;
+    uint256 totalSupplyAtoken;
+  }
+
   /**
    * @dev Validates the health factor of a user and the exposure cap for the asset being withdrawn
+   * @param asset The asset for which the exposure cap will be validated
+   * @param expCapOffset The offset to consider on the total atoken supply of asset when validating the exposure cap
    * @param from The user from which the aTokens are being transferred
    * @param reservesData The state of all the reserves
    * @param userConfig The state of the user for the specific reserve
@@ -517,7 +528,8 @@ library ValidationLogic {
    * @param oracle The price oracle
    */
   function validateHFAndExposureCap(
-    address collateral,
+    address asset,
+    uint256 expCapOffset,
     address from,
     mapping(address => DataTypes.ReserveData) storage reservesData,
     DataTypes.UserConfigurationMap storage userConfig,
@@ -525,30 +537,31 @@ library ValidationLogic {
     uint256 reservesCount,
     address oracle
   ) external view {
-    DataTypes.ReserveData memory reserve = reservesData[collateral];
+    validateHFAndExposureCapLocalVars memory vars;
-    (, , uint256 ltv, uint256 liquidationThreshold, uint256 healthFactor, uint256 uncappedLtv) =
+    DataTypes.ReserveData memory reserve = reservesData[asset];
-      GenericLogic.calculateUserAccountData(
+    (, , vars.ltv, , vars.healthFactor, vars.uncappedLtv) = GenericLogic.calculateUserAccountData(
-        from,
+      from,
-        reservesData,
+      reservesData,
-        userConfig,
+      userConfig,
-        reserves,
+      reserves,
-        reservesCount,
+      reservesCount,
-        oracle
+      oracle
-      );
+    );
-
 
     require(
-      healthFactor >= GenericLogic.HEALTH_FACTOR_LIQUIDATION_THRESHOLD,
+      vars.healthFactor >= GenericLogic.HEALTH_FACTOR_LIQUIDATION_THRESHOLD,
       Errors.VL_HEALTH_FACTOR_LOWER_THAN_LIQUIDATION_THRESHOLD
     );
 
-    uint256 exposureCap = reserve.configuration.getExposureCapMemory();
+    vars.exposureCap = reserve.configuration.getExposureCapMemory();
 
-    if (exposureCap != 0) {
+    if (vars.exposureCap != 0) {
-      if (ltv < uncappedLtv) {
+      if (vars.ltv < vars.uncappedLtv) {
-        uint256 totalSupplyAtoken = IERC20(reserve.aTokenAddress).totalSupply();
+        vars.totalSupplyAtoken = IERC20(reserve.aTokenAddress).totalSupply();
-        (, , , uint256 reserveDecimals, ) = reserve.configuration.getParamsMemory();
+        (, , , vars.reserveDecimals, ) = reserve.configuration.getParamsMemory();
-        bool isAssetCapped = totalSupplyAtoken.div(10**reserveDecimals) >= exposureCap;
+        bool isAssetCapped =
+          vars.totalSupplyAtoken.sub(expCapOffset).div(10**vars.reserveDecimals) >=
+            vars.exposureCap;
         require(isAssetCapped, Errors.VL_COLLATERAL_EXPOSURE_CAP_EXCEEDED);
       }
     }