From 59b87a27efea819e433c727756bf5fac57b33dd6 Mon Sep 17 00:00:00 2001
From: John Newbery <john@johnnewbery.com>
Date: Mon, 7 May 2018 17:08:03 -0400
Subject: [PATCH] [wallet] Fix potential memory leak in CreateWalletFromFile

Fix proposed by ryanofsky in
https://github.com/bitcoin/bitcoin/pull/12647#discussion_r174875670
---
 src/wallet/wallet.cpp | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/src/wallet/wallet.cpp b/src/wallet/wallet.cpp
index 5be9f4a29..f9f567009 100644
--- a/src/wallet/wallet.cpp
+++ b/src/wallet/wallet.cpp
@@ -4012,7 +4012,10 @@ CWallet* CWallet::CreateWalletFromFile(const std::string& name, const fs::path&
 
     int64_t nStart = GetTimeMillis();
     bool fFirstRun = true;
-    CWallet *walletInstance = new CWallet(name, WalletDatabase::Create(path));
+    // Make a temporary wallet unique pointer so memory doesn't get leaked if
+    // wallet creation fails.
+    auto temp_wallet = MakeUnique<CWallet>(name, WalletDatabase::Create(path));
+    CWallet* walletInstance = temp_wallet.get();
     DBErrors nLoadWalletRet = walletInstance->LoadWallet(fFirstRun);
     if (nLoadWalletRet != DBErrors::LOAD_OK)
     {
@@ -4224,7 +4227,6 @@ CWallet* CWallet::CreateWalletFromFile(const std::string& name, const fs::path&
     }
 
     walletInstance->m_last_block_processed = chainActive.Tip();
-    RegisterValidationInterface(walletInstance);
 
     if (chainActive.Tip() && chainActive.Tip() != pindexRescan)
     {
@@ -4290,6 +4292,10 @@ CWallet* CWallet::CreateWalletFromFile(const std::string& name, const fs::path&
             }
         }
     }
+
+    // Register with the validation interface. It's ok to do this after rescan since we're still holding cs_main.
+    RegisterValidationInterface(temp_wallet.release());
+
     walletInstance->SetBroadcastTransactions(gArgs.GetBoolArg("-walletbroadcast", DEFAULT_WALLETBROADCAST));
 
     {