Fix missing lock in submitblock

src/rpcmining.cpp

@@ -629,6 +629,9 @@ Value submitblock(const Array& params, bool fHelp)
         throw JSONRPCError(RPC_DESERIALIZATION_ERROR, "Block decode failed");
 
     uint256 hash = block.GetHash();
+    bool fBlockPresent = false;
+    {
+        LOCK(cs_main);
         BlockMap::iterator mi = mapBlockIndex.find(hash);
         if (mi != mapBlockIndex.end()) {
             CBlockIndex *pindex = mi->second;
@@ -637,6 +640,8 @@ Value submitblock(const Array& params, bool fHelp)
             if (pindex->nStatus & BLOCK_FAILED_MASK)
                 return "duplicate-invalid";
             // Otherwise, we might only have the header - process the block before returning
+            fBlockPresent = true;
+        }
     }
 
     CValidationState state;
@@ -644,7 +649,7 @@ Value submitblock(const Array& params, bool fHelp)
     RegisterValidationInterface(&sc);
     bool fAccepted = ProcessNewBlock(state, NULL, &block);
     UnregisterValidationInterface(&sc);
-    if (mi != mapBlockIndex.end())
+    if (fBlockPresent)
     {
         if (fAccepted && !sc.found)
             return "duplicate-inconclusive";