From e2f30d547f733ee33e7814ab500c08d12958e66a Mon Sep 17 00:00:00 2001
From: Pieter Wuille <pieter.wuille@gmail.com>
Date: Tue, 18 Nov 2014 16:30:51 +0100
Subject: [PATCH] Properly lock cs_main in rest_block

---
 src/rest.cpp | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/src/rest.cpp b/src/rest.cpp
index 89075887a..9a8793a51 100644
--- a/src/rest.cpp
+++ b/src/rest.cpp
@@ -11,6 +11,7 @@
 #include "core/transaction.h"
 #include "version.h"
 #include "main.h"
+#include "sync.h"
 
 using namespace std;
 using namespace json_spirit;
@@ -80,13 +81,17 @@ static bool rest_block(AcceptedConnection *conn,
     if (!ParseHashStr(hashStr, hash))
         throw RESTERR(HTTP_BAD_REQUEST, "Invalid hash: " + hashStr);
 
-    if (mapBlockIndex.count(hash) == 0)
-        throw RESTERR(HTTP_NOT_FOUND, hashStr + " not found");
-
     CBlock block;
-    CBlockIndex* pblockindex = mapBlockIndex[hash];
-    if (!ReadBlockFromDisk(block, pblockindex))
-        throw RESTERR(HTTP_NOT_FOUND, hashStr + " not found");
+    CBlockIndex* pblockindex = NULL;
+    {
+        LOCK(cs_main);
+        if (mapBlockIndex.count(hash) == 0)
+            throw RESTERR(HTTP_NOT_FOUND, hashStr + " not found");
+
+        pblockindex = mapBlockIndex[hash];
+        if (!ReadBlockFromDisk(block, pblockindex))
+            throw RESTERR(HTTP_NOT_FOUND, hashStr + " not found");
+    }
 
     CDataStream ssBlock(SER_NETWORK, PROTOCOL_VERSION);
     ssBlock << block;