From c5ed6e73d3e18f26558c49fa3ecb1b7b0bb40d12 Mon Sep 17 00:00:00 2001
From: Hennadii Stepanov <32963518+hebasto@users.noreply.github.com>
Date: Thu, 29 Nov 2018 13:36:12 +0200
Subject: [PATCH] Move CheckBlock() call to critical section

This prevents data race for CBlock::fChecked.
---
 src/validation.cpp               | 8 +++++---
 test/sanitizer_suppressions/tsan | 3 ---
 2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/src/validation.cpp b/src/validation.cpp
index 6333dd98d2..512a3619ca 100644
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -3530,12 +3530,14 @@ bool ProcessNewBlock(const CChainParams& chainparams, const std::shared_ptr<cons
         CBlockIndex *pindex = nullptr;
         if (fNewBlock) *fNewBlock = false;
         CValidationState state;
+
+        // CheckBlock() does not support multi-threaded block validation because CBlock::fChecked can cause data race.
+        // Therefore, the following critical section must include the CheckBlock() call as well.
+        LOCK(cs_main);
+
         // Ensure that CheckBlock() passes before calling AcceptBlock, as
         // belt-and-suspenders.
         bool ret = CheckBlock(*pblock, state, chainparams.GetConsensus());
-
-        LOCK(cs_main);
-
         if (ret) {
             // Store to disk
             ret = g_chainstate.AcceptBlock(pblock, state, chainparams, &pindex, fForceProcessing, nullptr, fNewBlock);
diff --git a/test/sanitizer_suppressions/tsan b/test/sanitizer_suppressions/tsan
index 209c46f096..996f342eb9 100644
--- a/test/sanitizer_suppressions/tsan
+++ b/test/sanitizer_suppressions/tsan
@@ -1,9 +1,6 @@
 # ThreadSanitizer suppressions
 # ============================
 
-# fChecked is theoretically racy, practically only in unit tests
-race:CheckBlock
-
 # WalletBatch (unidentified deadlock)
 deadlock:WalletBatch