Fix some locks

sipa · Fuzzbawls · commit 58044ac7c58f · 2020-08-25T15:09:34.000-07:00
This makes sure that cs_filter is never held while taking cs_main
or CNode::cs_vSend.
diff --git a/src/main.cpp b/src/main.cpp
@@ -5017,9 +5017,16 @@ void static ProcessGetData(CNode* pfrom)
                         pfrom->PushMessage(NetMsgType::BLOCK, block);
                     else // MSG_FILTERED_BLOCK)
                     {
-                        LOCK(pfrom->cs_filter);
-                        if (pfrom->pfilter) {
-                            CMerkleBlock merkleBlock(block, *pfrom->pfilter);
+                        bool send = false;
+                        CMerkleBlock merkleBlock;
+                        {
+                            LOCK(pfrom->cs_filter);
+                            if (pfrom->pfilter) {
+                                send = true;
+                                merkleBlock = CMerkleBlock(block, *pfrom->pfilter);
+                            }
+                        }
+                        if (send) {
                             pfrom->PushMessage(NetMsgType::MERKLEBLOCK, merkleBlock);
                             // CMerkleBlock just contains hashes, so also push any transactions in the block the client did not see
                             // This avoids hurting performance by pointlessly requiring a round-trip
@@ -5940,8 +5947,8 @@ bool static ProcessMessage(CNode* pfrom, std::string strCommand, CDataStream& vR
             delete pfrom->pfilter;
             pfrom->pfilter = new CBloomFilter(filter);
             pfrom->pfilter->UpdateEmptyFull();
+            pfrom->fRelayTxes = true;
         }
-        pfrom->fRelayTxes = true;
     }
 
 
@@ -5951,18 +5958,21 @@ bool static ProcessMessage(CNode* pfrom, std::string strCommand, CDataStream& vR
 
         // Nodes must NEVER send a data item > 520 bytes (the max size for a script data object,
         // and thus, the maximum size any matched object can have) in a filteradd message
+        bool bad = false;
         if (vData.size() > MAX_SCRIPT_ELEMENT_SIZE) {
-            LOCK(cs_main);
-            Misbehaving(pfrom->GetId(), 100);
+            bad = true;
         } else {
             LOCK(pfrom->cs_filter);
-            if (pfrom->pfilter)
+            if (pfrom->pfilter) {
                 pfrom->pfilter->insert(vData);
-            else {
-                LOCK(cs_main);
-                Misbehaving(pfrom->GetId(), 100);
+            } else {
+                bad = true;
             }
         }
+        if (bad) {
+            LOCK(cs_main);
+            Misbehaving(pfrom->GetId(), 100);
+        }
     }
 
 
diff --git a/src/merkleblock.h b/src/merkleblock.h
@@ -141,6 +141,8 @@ class CMerkleBlock
      */
     CMerkleBlock(const CBlock& block, CBloomFilter& filter);
 
+    CMerkleBlock() {}
+
     ADD_SERIALIZE_METHODS;
 
     template <typename Stream, typename Operation>
