fix use-after-free

src/Interpreters/AsynchronousInsertQueue.cpp

@@ -407,14 +407,20 @@ try
     }
 
     StreamingFormatExecutor executor(header, format, std::move(on_error), std::move(adding_defaults_transform));
-    std::unique_ptr<ReadBuffer> buffer;
+    std::unique_ptr<ReadBuffer> last_buffer;
     for (const auto & entry : data->entries)
     {
-        buffer = std::make_unique<ReadBufferFromString>(entry->bytes);
+        auto buffer = std::make_unique<ReadBufferFromString>(entry->bytes);
         current_entry = entry;
         total_rows += executor.execute(*buffer);
+
+        /// Keep buffer, because it still can be used
+        /// in destructor, while resetting buffer at next iteration.
+        last_buffer = std::move(buffer);
     }
 
+    format->addBuffer(std::move(last_buffer));
+
     auto chunk = Chunk(executor.getResultColumns(), total_rows);
     size_t total_bytes = chunk.bytes();