From bd5235a5a8603ad1a0d2d1ee3b6847ff98352209 Mon Sep 17 00:00:00 2001
From: Jon Atack <jon@atack.com>
Date: Tue, 18 Jan 2022 12:51:03 +0100
Subject: [PATCH] Require IsBlockPruned() to hold mutex cs_main

Summary:
Co-authored-by: Vasil Dimov <vd@FreeBSD.org>

This is a partial backport of [[https://github.com/bitcoin/bitcoin/pull/22932 | core#22932]]
https://github.com/bitcoin/bitcoin/pull/22932/commits/eaeeb88768db529b5241ccd42f1e87579908b4df

Depends on D13036

Test Plan:
With clang and DEBUG:

`ninja all check-all`

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Subscribers: Fabien

Differential Revision: https://reviews.bitcoinabc.org/D13037
---
 src/node/blockstorage.cpp |  1 +
 src/node/blockstorage.h   |  3 ++-
 src/rpc/blockchain.cpp    | 13 +++++++++----
 3 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/src/node/blockstorage.cpp b/src/node/blockstorage.cpp
index df52066e4f..f9e7a27295 100644
--- a/src/node/blockstorage.cpp
+++ b/src/node/blockstorage.cpp
@@ -398,6 +398,7 @@ BlockManager::GetLastCheckpoint(const CCheckpointData &data) {
 }
 
 bool IsBlockPruned(const CBlockIndex *pblockindex) {
+    AssertLockHeld(::cs_main);
     return (fHavePruned && !pblockindex->nStatus.hasData() &&
             pblockindex->nTx > 0);
 }
diff --git a/src/node/blockstorage.h b/src/node/blockstorage.h
index 2a813119c9..55d77dbd6b 100644
--- a/src/node/blockstorage.h
+++ b/src/node/blockstorage.h
@@ -197,7 +197,8 @@ class BlockManager {
 };
 
 //! Check whether the block associated with this index entry is pruned or not.
-bool IsBlockPruned(const CBlockIndex *pblockindex);
+bool IsBlockPruned(const CBlockIndex *pblockindex)
+    EXCLUSIVE_LOCKS_REQUIRED(::cs_main);
 
 void CleanupBlockRevFiles();
 
diff --git a/src/rpc/blockchain.cpp b/src/rpc/blockchain.cpp
index 348987f261..9363c6eed4 100644
--- a/src/rpc/blockchain.cpp
+++ b/src/rpc/blockchain.cpp
@@ -172,8 +172,9 @@ UniValue blockToJSON(const CBlock &block, const CBlockIndex *tip,
     UniValue txs(UniValue::VARR);
     if (txDetails) {
         CBlockUndo blockUndo;
-        const bool have_undo = !IsBlockPruned(blockindex) &&
-                               UndoReadFromDisk(blockUndo, blockindex);
+        const bool have_undo{WITH_LOCK(
+            ::cs_main, return !IsBlockPruned(blockindex) &&
+                              UndoReadFromDisk(blockUndo, blockindex))};
         for (size_t i = 0; i < block.vtx.size(); ++i) {
             const CTransactionRef &tx = block.vtx.at(i);
             // coinbase transaction (i == 0) doesn't have undo data
@@ -1065,7 +1066,9 @@ static RPCHelpMan getblockheader() {
 }
 
 static CBlock GetBlockChecked(const Config &config,
-                              const CBlockIndex *pblockindex) {
+                              const CBlockIndex *pblockindex)
+    EXCLUSIVE_LOCKS_REQUIRED(::cs_main) {
+    AssertLockHeld(::cs_main);
     CBlock block;
     if (IsBlockPruned(pblockindex)) {
         throw JSONRPCError(RPC_MISC_ERROR, "Block not available (pruned data)");
@@ -1082,7 +1085,9 @@ static CBlock GetBlockChecked(const Config &config,
     return block;
 }
 
-static CBlockUndo GetUndoChecked(const CBlockIndex *pblockindex) {
+static CBlockUndo GetUndoChecked(const CBlockIndex *pblockindex)
+    EXCLUSIVE_LOCKS_REQUIRED(cs_main) {
+    AssertLockHeld(::cs_main);
     CBlockUndo blockUndo;
     if (IsBlockPruned(pblockindex)) {
         throw JSONRPCError(RPC_MISC_ERROR,