From 2f8512b923bd9562328ebf49f2a21cac7b6d0d5d Mon Sep 17 00:00:00 2001
From: "Wladimir J. van der Laan" <laanwj@gmail.com>
Date: Mon, 28 Aug 2017 10:47:07 +0200
Subject: [PATCH] Merge #11126: Acquire cs_main lock before cs_wallet during
 wallet initialization

de9a1db Acquire cs_main lock before cs_wallet during wallet initialization (Russell Yanofsky)

Pull request description:

  `CWallet::MarkConflicted` may acquire the `cs_main` lock after `CWalletDB::LoadWallet` acquires the `cs_wallet` lock during wallet initialization. (`CWalletDB::LoadWallet` calls `ReadKeyValue` which calls `CWallet::LoadToWallet` which calls `CWallet::MarkConflicted`). This is the opposite order that `cs_main` and `cs_wallet` locks are acquired in the rest of the code, and so leads to `POTENTIAL DEADLOCK DETECTED` errors if bitcoin is built with `-DDEBUG_LOCKORDER`.

  This commit changes `CWallet::LoadWallet` (which calls `CWalletDB::LoadWallet`) to acquire both locks in the standard order.

  Error was reported by @luke-jr in https://botbot.me/freenode/bitcoin-core-dev/msg/90244330/

Tree-SHA512: 353fe21bc0a4a2828b41876897001a3c414d4b115ee7430925bd391d8bc396fca81661145d00996c1ba1a01516d9acf8b89fb5c3da27092f5f3aa7e37ef26ffa
---
 src/wallet/test/wallet_tests.cpp | 17 ++++++++++-------
 src/wallet/wallet.cpp            |  3 ++-
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/src/wallet/test/wallet_tests.cpp b/src/wallet/test/wallet_tests.cpp
index 84887f9a5..90e8dc6da 100644
--- a/src/wallet/test/wallet_tests.cpp
+++ b/src/wallet/test/wallet_tests.cpp
@@ -363,6 +363,12 @@ BOOST_AUTO_TEST_CASE(ApproximateBestSubset)
     empty_wallet();
 }
 
+static void AddKey(CWallet& wallet, const CKey& key)
+{
+    LOCK(wallet.cs_wallet);
+    wallet.AddKeyPubKey(key, key.GetPubKey());
+}
+
 BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
 {
     // Cap last block file size, and mine new block in a new block file.
@@ -378,8 +384,7 @@ BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
     // and new block files.
     {
         CWallet wallet;
-        LOCK(wallet.cs_wallet);
-        wallet.AddKeyPubKey(coinbaseKey, coinbaseKey.GetPubKey());
+        AddKey(wallet, coinbaseKey);
         BOOST_CHECK_EQUAL(nullBlock, wallet.ScanForWalletTransactions(oldTip));
         BOOST_CHECK_EQUAL(wallet.GetImmatureBalance(), 1000 * COIN);
     }
@@ -392,8 +397,7 @@ BOOST_FIXTURE_TEST_CASE(rescan, TestChain100Setup)
     // file.
     {
         CWallet wallet;
-        LOCK(wallet.cs_wallet);
-        wallet.AddKeyPubKey(coinbaseKey, coinbaseKey.GetPubKey());
+        AddKey(wallet, coinbaseKey);
         BOOST_CHECK_EQUAL(oldTip, wallet.ScanForWalletTransactions(oldTip));
         BOOST_CHECK_EQUAL(wallet.GetImmatureBalance(), 500 * COIN);
     }
@@ -598,8 +602,7 @@ public:
         wallet.reset(new CWallet(std::unique_ptr<CWalletDBWrapper>(new CWalletDBWrapper(&bitdb, "wallet_test.dat"))));
         bool firstRun;
         wallet->LoadWallet(firstRun);
-        LOCK(wallet->cs_wallet);
-        wallet->AddKeyPubKey(coinbaseKey, coinbaseKey.GetPubKey());
+        AddKey(*wallet, coinbaseKey);
         wallet->ScanForWalletTransactions(chainActive.Genesis());
     }
 
@@ -633,7 +636,7 @@ public:
 BOOST_FIXTURE_TEST_CASE(ListCoins, ListCoinsTestingSetup)
 {
     std::string coinbaseAddress = coinbaseKey.GetPubKey().GetID().ToString();
-    LOCK(wallet->cs_wallet);
+    LOCK2(cs_main, wallet->cs_wallet);
 
     // Confirm ListCoins initially returns 1 coin grouped under coinbaseKey
     // address.
diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 34c04c666..7b659b92a 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -3952,13 +3952,14 @@ CAmount CWallet::GetMinimumFee(unsigned int nTxBytes, unsigned int nConfirmTarge
 
 DBErrors CWallet::LoadWallet(bool& fFirstRunRet)
 {
+    LOCK2(cs_main, cs_wallet);
+
     fFirstRunRet = false;
     DBErrors nLoadWalletRet = CWalletDB(*dbw,"cr+").LoadWallet(this);
     if (nLoadWalletRet == DB_NEED_REWRITE)
     {
         if (dbw->Rewrite("\x04pool"))
         {
-            LOCK(cs_wallet);
             setInternalKeyPool.clear();
             setExternalKeyPool.clear();
             nKeysLeftSinceAutoBackup = 0;