From 588eb30b863e9ecf942396158adfc7f6f047d3e2 Mon Sep 17 00:00:00 2001
From: Alexander Block <ablock84@gmail.com>
Date: Mon, 11 Mar 2019 14:31:51 +0100
Subject: [PATCH] Fix deadlock in CSigSharesManager::SendMessages (#2757)

* Fix deadlock in CSigSharesManager::SendMessages

Locking "cs" at this location caused a (potential) deadlock due to changed
order of cs and cs_vNodes locking. This changes the method to not require
the session object anymore which removes the need for locking.

* Pass size of LLMQ instead of llmqType into CSigSharesInv::Init

This allows use of sizes which are not supported in chainparams.
---
 src/llmq/quorums_signing_shares.cpp | 38 ++++++++++++++---------------
 src/llmq/quorums_signing_shares.h   |  4 +--
 2 files changed, 20 insertions(+), 22 deletions(-)

diff --git a/src/llmq/quorums_signing_shares.cpp b/src/llmq/quorums_signing_shares.cpp
index ca52d29338..59ca1f3fac 100644
--- a/src/llmq/quorums_signing_shares.cpp
+++ b/src/llmq/quorums_signing_shares.cpp
@@ -65,10 +65,9 @@ std::string CSigSharesInv::ToString() const
     return str;
 }
 
-void CSigSharesInv::Init(Consensus::LLMQType _llmqType)
+void CSigSharesInv::Init(size_t size)
 {
-    size_t llmqSize = (size_t)(Params().GetConsensus().llmqs.at(_llmqType).size);
-    inv.resize(llmqSize, false);
+    inv.resize(size, false);
 }
 
 bool CSigSharesInv::IsSet(uint16_t quorumMember) const
@@ -83,27 +82,30 @@ void CSigSharesInv::Set(uint16_t quorumMember, bool v)
     inv[quorumMember] = v;
 }
 
-CSigSharesInv CBatchedSigShares::ToInv(Consensus::LLMQType llmqType) const
+std::string CBatchedSigShares::ToInvString() const
 {
     CSigSharesInv inv;
-    inv.Init(llmqType);
+    // we use 400 here no matter what the real size is. We don't really care about that size as we just want to call ToString()
+    inv.Init(400);
     for (size_t i = 0; i < sigShares.size(); i++) {
         inv.inv[sigShares[i].first] = true;
     }
-    return inv;
+    return inv.ToString();
 }
 
 template<typename T>
 static void InitSession(CSigSharesNodeState::Session& s, const uint256& signHash, T& from)
 {
+    const auto& params = Params().GetConsensus().llmqs.at((Consensus::LLMQType)from.llmqType);
+
     s.llmqType = (Consensus::LLMQType)from.llmqType;
     s.quorumHash = from.quorumHash;
     s.id = from.id;
     s.msgHash = from.msgHash;
     s.signHash = signHash;
-    s.announced.Init((Consensus::LLMQType)from.llmqType);
-    s.requested.Init((Consensus::LLMQType)from.llmqType);
-    s.knows.Init((Consensus::LLMQType)from.llmqType);
+    s.announced.Init((size_t)params.size);
+    s.requested.Init((size_t)params.size);
+    s.knows.Init((size_t)params.size);
 }
 
 CSigSharesNodeState::Session& CSigSharesNodeState::GetOrCreateSessionFromShare(const llmq::CSigShare& sigShare)
@@ -443,7 +445,7 @@ bool CSigSharesManager::ProcessMessageBatchedSigShares(CNode* pfrom, const CBatc
     }
 
     LogPrint("llmq", "CSigSharesManager::%s -- signHash=%s, shares=%d, new=%d, inv={%s}, node=%d\n", __func__,
-             sessionInfo.signHash.ToString(), batchedSigShares.sigShares.size(), sigShares.size(), batchedSigShares.ToInv(sessionInfo.llmqType).ToString(), pfrom->id);
+             sessionInfo.signHash.ToString(), batchedSigShares.sigShares.size(), sigShares.size(), batchedSigShares.ToInvString(), pfrom->id);
 
     if (sigShares.empty()) {
         return true;
@@ -871,7 +873,8 @@ void CSigSharesManager::CollectSigSharesToRequest(std::unordered_map<NodeId, std
                 }
                 auto& inv = (*invMap)[signHash];
                 if (inv.inv.empty()) {
-                    inv.Init(session.llmqType);
+                    const auto& params = Params().GetConsensus().llmqs.at((Consensus::LLMQType)session.llmqType);
+                    inv.Init((size_t)params.size);
                 }
                 inv.inv[k.second] = true;
 
@@ -982,7 +985,8 @@ void CSigSharesManager::CollectSigSharesToAnnounce(std::unordered_map<NodeId, st
 
             auto& inv = sigSharesToAnnounce[nodeId][signHash];
             if (inv.inv.empty()) {
-                inv.Init((Consensus::LLMQType)sigShare->llmqType);
+                const auto& params = Params().GetConsensus().llmqs.at((Consensus::LLMQType)sigShare->llmqType);
+                inv.Init((size_t)params.size);
             }
             inv.inv[quorumMember] = true;
             session.knows.inv[quorumMember] = true;
@@ -1101,14 +1105,8 @@ bool CSigSharesManager::SendMessages()
             std::vector<CBatchedSigShares> msgs;
             for (auto& p : jt->second) {
                 assert(!p.second.sigShares.empty());
-                if (LogAcceptCategory("llmq")) {
-                    LOCK(cs);
-                    auto session = nodeStates[pnode->id].GetSessionBySignHash(p.first);
-                    assert(session);
-                    LogPrint("llmq", "CSigSharesManager::SendMessages -- QBSIGSHARES signHash=%s, inv={%s}, node=%d\n",
-                             p.first.ToString(), p.second.ToInv(session->llmqType).ToString(), pnode->id);
-                }
-
+                LogPrint("llmq", "CSigSharesManager::SendMessages -- QBSIGSHARES signHash=%s, inv={%s}, node=%d\n",
+                         p.first.ToString(), p.second.ToInvString(), pnode->id);
                 if (totalSigsCount + p.second.sigShares.size() > MAX_MSGS_TOTAL_BATCHED_SIGS) {
                     g_connman->PushMessage(pnode, msgMaker.Make(NetMsgType::QBSIGSHARES, msgs), false);
                     msgs.clear();
diff --git a/src/llmq/quorums_signing_shares.h b/src/llmq/quorums_signing_shares.h
index beb781589d..d17be73c82 100644
--- a/src/llmq/quorums_signing_shares.h
+++ b/src/llmq/quorums_signing_shares.h
@@ -101,7 +101,7 @@ public:
         READWRITE(AUTOBITSET(inv, (size_t)invSize));
     }
 
-    void Init(Consensus::LLMQType _llmqType);
+    void Init(size_t size);
     bool IsSet(uint16_t quorumMember) const;
     void Set(uint16_t quorumMember, bool v);
     void Merge(const CSigSharesInv& inv2);
@@ -127,7 +127,7 @@ public:
         READWRITE(sigShares);
     }
 
-    CSigSharesInv ToInv(Consensus::LLMQType llmqType) const;
+    std::string ToInvString() const;
 };
 
 template<typename T>