src: Check return value from nghttp2_session_get_stream_user_data

src/h2load_http2_session.cc

@@ -119,7 +119,7 @@ ssize_t file_read_callback(nghttp2_session *session, int32_t stream_id,
   auto config = client->worker->config;
   auto req_stat = static_cast<RequestStat *>(
       nghttp2_session_get_stream_user_data(session, stream_id));
-
+  assert(req_stat);
   ssize_t nread;
   while ((nread = pread(config->data_fd, buf, length, req_stat->data_offset)) ==
              -1 &&

src/shrpx_http2_upstream.cc

@@ -500,6 +500,10 @@ int on_frame_send_callback(nghttp2_session *session, const nghttp2_frame *frame,
     auto downstream = static_cast<Downstream *>(
         nghttp2_session_get_stream_user_data(session, stream_id));
 
+    if (!downstream) {
+      return 0;
+    }
+
     // For tunneling, issue RST_STREAM to finish the stream.
     if (downstream->get_upgraded() ||
         nghttp2_session_get_stream_remote_close(session, stream_id) == 0) {