Release cs_main before processing cmpctblock as header

src/net_processing.cpp

@@ -1789,6 +1789,11 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
         bool fProcessBLOCKTXN = false;
         CDataStream blockTxnMsg(SER_NETWORK, PROTOCOL_VERSION);
 
+        // If we end up treating this as a plain headers message, call that as well
+        // without cs_main.
+        bool fRevertToHeaderProcessing = false;
+        CDataStream vHeadersMsg(SER_NETWORK, PROTOCOL_VERSION);
+
         // Keep a CBlock for "optimistic" compactblock reconstructions (see
         // below)
         std::shared_ptr<CBlock> pblock = std::make_shared<CBlock>();
@@ -1913,9 +1918,8 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
                 // Dirty hack to process as if it were just a headers message (TODO: move message handling into their own functions)
                 std::vector<CBlock> headers;
                 headers.push_back(cmpctblock.header);
-                CDataStream vHeadersMsg(SER_NETWORK, PROTOCOL_VERSION);
                 vHeadersMsg << headers;
-                return ProcessMessage(pfrom, NetMsgType::HEADERS, vHeadersMsg, nTimeReceived, chainparams, connman);
+                fRevertToHeaderProcessing = true;
             }
         }
         } // cs_main
@@ -1923,6 +1927,9 @@ bool static ProcessMessage(CNode* pfrom, string strCommand, CDataStream& vRecv,
         if (fProcessBLOCKTXN)
             return ProcessMessage(pfrom, NetMsgType::BLOCKTXN, blockTxnMsg, nTimeReceived, chainparams, connman);
 
+        if (fRevertToHeaderProcessing)
+            return ProcessMessage(pfrom, NetMsgType::HEADERS, vHeadersMsg, nTimeReceived, chainparams, connman);
+
         if (fBlockReconstructed) {
             // If we got here, we were able to optimistically reconstruct a
             // block that is in flight from some other peer.