From 2530bf27b72e53cc6ffec27de35f3b487984833d Mon Sep 17 00:00:00 2001
From: practicalswift <practicalswift@users.noreply.github.com>
Date: Mon, 30 Oct 2017 14:28:19 +0100
Subject: [PATCH] net: Add missing lock in ProcessHeadersMessage(...)

Reading the variable mapBlockIndex requires holding the mutex cs_main.

The new "Disconnect outbound peers relaying invalid headers" code
added in commit 37886d5e2f9992678dea4b1bd893f4f10d61d3ad and merged
as part of #11568 two days ago did not lock cs_main prior to accessing
mapBlockIndex.
---
 src/net_processing.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/net_processing.cpp b/src/net_processing.cpp
index 4c3aacaf5..92b7a75f7 100644
--- a/src/net_processing.cpp
+++ b/src/net_processing.cpp
@@ -1262,8 +1262,8 @@ bool static ProcessHeadersMessage(CNode *pfrom, CConnman *connman, const std::ve
     if (!ProcessNewBlockHeaders(headers, state, chainparams, &pindexLast, &first_invalid_header)) {
         int nDoS;
         if (state.IsInvalid(nDoS)) {
+            LOCK(cs_main);
             if (nDoS > 0) {
-                LOCK(cs_main);
                 Misbehaving(pfrom->GetId(), nDoS);
             }
             if (punish_duplicate_invalid && mapBlockIndex.find(first_invalid_header.GetHash()) != mapBlockIndex.end()) {