From d8f8f174c096770fea1dc6da9d09431d9f4d494b Mon Sep 17 00:00:00 2001
From: UdjinM6 <UdjinM6@users.noreply.github.com>
Date: Wed, 28 Oct 2020 22:01:29 +0300
Subject: [PATCH] Avoid accessing pendingContributionVerifications from
 VerifyPendingContributions while ReceiveMessage is still doing its job
 (#3782)

---
 src/llmq/quorums_dkgsession.cpp | 9 ++++++++-
 src/llmq/quorums_dkgsession.h   | 1 +
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/src/llmq/quorums_dkgsession.cpp b/src/llmq/quorums_dkgsession.cpp
index 4859497f1d..8871071187 100644
--- a/src/llmq/quorums_dkgsession.cpp
+++ b/src/llmq/quorums_dkgsession.cpp
@@ -260,6 +260,8 @@ bool CDKGSession::PreVerifyMessage(const uint256& hash, const CDKGContribution&
 
 void CDKGSession::ReceiveMessage(const uint256& hash, const CDKGContribution& qc, bool& retBan)
 {
+    LOCK(cs_pending);
+
     CDKGLogger logger(*this, __func__);
 
     retBan = false;
@@ -359,6 +361,8 @@ void CDKGSession::ReceiveMessage(const uint256& hash, const CDKGContribution& qc
 // See CBLSWorker::VerifyContributionShares for more details.
 void CDKGSession::VerifyPendingContributions()
 {
+    AssertLockHeld(cs_pending);
+
     CDKGLogger logger(*this, __func__);
 
     cxxtimer::Timer t1(true);
@@ -412,7 +416,10 @@ void CDKGSession::VerifyAndComplain(CDKGPendingMessages& pendingMessages)
         return;
     }
 
-    VerifyPendingContributions();
+    {
+        LOCK(cs_pending);
+        VerifyPendingContributions();
+    }
 
     CDKGLogger logger(*this, __func__);
 
diff --git a/src/llmq/quorums_dkgsession.h b/src/llmq/quorums_dkgsession.h
index b70f7d7942..6525f6eb89 100644
--- a/src/llmq/quorums_dkgsession.h
+++ b/src/llmq/quorums_dkgsession.h
@@ -277,6 +277,7 @@ private:
     std::map<uint256, CDKGJustification> justifications;
     std::map<uint256, CDKGPrematureCommitment> prematureCommitments;
 
+    mutable CCriticalSection cs_pending;
     std::vector<size_t> pendingContributionVerifications;
 
     // filled by ReceivePrematureCommitment and used by FinalizeCommitments