- Added nonReentrant modifier on StaticAToken external functions

contracts/dependencies/openzeppelin/contracts/ReentrancyGuard.sol

@@ -0,0 +1,65 @@
+// SPDX-License-Identifier: MIT
+
+pragma solidity 0.6.12;
+
+// From version of 12/04/2021 on https://github.com/OpenZeppelin/openzeppelin-contracts/commit/555be63c909cc29617d828df62052f0b95147e50
+// Adapting syntax to 0.6.12
+
+/**
+ * @dev Contract module that helps prevent reentrant calls to a function.
+ *
+ * Inheriting from `ReentrancyGuard` will make the {nonReentrant} modifier
+ * available, which can be applied to functions to make sure there are no nested
+ * (reentrant) calls to them.
+ *
+ * Note that because there is a single `nonReentrant` guard, functions marked as
+ * `nonReentrant` may not call one another. This can be worked around by making
+ * those functions `private`, and then adding `external` `nonReentrant` entry
+ * points to them.
+ *
+ * TIP: If you would like to learn more about reentrancy and alternative ways
+ * to protect against it, check out our blog post
+ * https://blog.openzeppelin.com/reentrancy-after-istanbul/[Reentrancy After Istanbul].
+ */
+abstract contract ReentrancyGuard {
+  // Booleans are more expensive than uint256 or any type that takes up a full
+  // word because each write operation emits an extra SLOAD to first read the
+  // slot's contents, replace the bits taken up by the boolean, and then write
+  // back. This is the compiler's defense against contract upgrades and
+  // pointer aliasing, and it cannot be disabled.
+
+  // The values being non-zero value makes deployment a bit more expensive,
+  // but in exchange the refund on every call to nonReentrant will be lower in
+  // amount. Since refunds are capped to a percentage of the total
+  // transaction's gas, it is best to keep them low in cases like this one, to
+  // increase the likelihood of the full refund coming into effect.
+  uint256 private constant _NOT_ENTERED = 1;
+  uint256 private constant _ENTERED = 2;
+
+  uint256 private _status;
+
+  constructor() public {
+    _status = _NOT_ENTERED;
+  }
+
+  /**
+   * @dev Prevents a contract from calling itself, directly or indirectly.
+   * Calling a `nonReentrant` function from another `nonReentrant`
+   * function is not supported. It is possible to prevent this from happening
+   * by making the `nonReentrant` function external, and make it call a
+   * `private` function that does the actual work.
+   */
+  modifier nonReentrant() {
+    // On the first call to nonReentrant, _notEntered will be true
+    require(_status != _ENTERED, 'ReentrancyGuard: reentrant call');
+
+    // Any calls to nonReentrant after this point will fail
+    _status = _ENTERED;
+
+    _;
+
+    // By storing the original value once again, a refund is triggered (see
+    // https://eips.ethereum.org/EIPS/eip-2200)
+    _status = _NOT_ENTERED;
+  }
+}

contracts/protocol/tokenization/StaticAToken.sol

@@ -7,6 +7,7 @@ import {IStaticAToken} from '../../interfaces/IStaticAToken.sol';
 import {IERC20} from '../../dependencies/openzeppelin/contracts/IERC20.sol';
 import {IAToken} from '../../interfaces/IAToken.sol';
 import {ERC20} from '../../dependencies/openzeppelin/contracts/ERC20.sol';
+import {ReentrancyGuard} from '../../dependencies/openzeppelin/contracts/ReentrancyGuard.sol';
 import {SafeERC20} from '../../dependencies/openzeppelin/contracts/SafeERC20.sol';
 import {WadRayMath} from '../../protocol/libraries/math/WadRayMath.sol';
 
@@ -17,7 +18,7 @@ import {WadRayMath} from '../../protocol/libraries/math/WadRayMath.sol';
  * - Only supporting deposits and withdrawals
  * @author Aave
  **/
-contract StaticAToken is IStaticAToken, ERC20 {
+contract StaticAToken is IStaticAToken, ReentrancyGuard, ERC20 {
   using SafeERC20 for IERC20;
   using WadRayMath for uint256;
 
@@ -73,7 +74,7 @@ contract StaticAToken is IStaticAToken, ERC20 {
     uint256 amount,
     uint16 referralCode,
     bool fromUnderlying
-  ) external override returns (uint256) {
+  ) external override nonReentrant returns (uint256) {
     return _deposit(msg.sender, recipient, amount, referralCode, fromUnderlying);
   }
 
@@ -91,7 +92,7 @@ contract StaticAToken is IStaticAToken, ERC20 {
     address recipient,
     uint256 amount,
     bool toUnderlying
-  ) external override returns (uint256, uint256) {
+  ) external override nonReentrant returns (uint256, uint256) {
     return _withdraw(msg.sender, recipient, amount, 0, toUnderlying);
   }
 
@@ -109,7 +110,7 @@ contract StaticAToken is IStaticAToken, ERC20 {
     address recipient,
     uint256 amount,
     bool toUnderlying
-  ) external override returns (uint256, uint256) {
+  ) external override nonReentrant returns (uint256, uint256) {
     return _withdraw(msg.sender, recipient, 0, amount, toUnderlying);
   }
 
@@ -177,7 +178,7 @@ contract StaticAToken is IStaticAToken, ERC20 {
     uint256 deadline,
     SignatureParams calldata sigParams,
     uint256 chainId
-  ) external override returns (uint256) {
+  ) external override nonReentrant returns (uint256) {
     require(depositor != address(0), 'INVALID_DEPOSITOR');
     //solium-disable-next-line
     require(block.timestamp <= deadline, 'INVALID_EXPIRATION');
@@ -234,7 +235,7 @@ contract StaticAToken is IStaticAToken, ERC20 {
     uint256 deadline,
     SignatureParams calldata sigParams,
     uint256 chainId
-  ) external override returns (uint256, uint256) {
+  ) external override nonReentrant returns (uint256, uint256) {
     require(owner != address(0), 'INVALID_DEPOSITOR');
     //solium-disable-next-line
     require(block.timestamp <= deadline, 'INVALID_EXPIRATION');

package.json

@@ -33,7 +33,7 @@
     "test-weth": "hardhat test test/__setup.spec.ts test/weth-gateway.spec.ts",
     "test-uniswap": "hardhat test test/__setup.spec.ts test/uniswapAdapters*.spec.ts",
     "test:main:check-list": "MAINNET_FORK=true TS_NODE_TRANSPILE_ONLY=1 hardhat test  test/__setup.spec.ts test/mainnet/check-list.spec.ts",
-    "test:main:staticAToken": "MAINNET_FORK=true FORKING_BLOCK=12063148 TS_NODE_TRANSPILE_ONLY=1 hardhat test test/mainnet/static-atoken.spec.ts",
+    "test:main:staticAToken": "MAINNET_FORK=true FORKING_BLOCK=12225650 TS_NODE_TRANSPILE_ONLY=1 hardhat test test/mainnet/static-atoken.spec.ts",
     "dev:coverage": "buidler compile --force && buidler coverage --network coverage",
     "aave:evm:dev:migration": "npm run compile && hardhat aave:dev",
     "aave:docker:full:migration": "npm run compile && npm run hardhat:docker -- aave:mainnet",