demos: Set size of uniform buffer in cube
diff --git a/demos/cube.c b/demos/cube.c
index 8cf8901..83244ff 100644
--- a/demos/cube.c
+++ b/demos/cube.c
@@ -1245,6 +1245,7 @@
     memset(&buf_info, 0, sizeof(buf_info));
     buf_info.sType = VK_STRUCTURE_TYPE_BUFFER_CREATE_INFO;
     buf_info.usage = VK_BUFFER_USAGE_UNIFORM_BUFFER_BIT;
+    buf_info.size = sizeof(data);
     err = vkCreateBuffer(demo->device, &buf_info, &demo->uniform_data.buf);
     assert(!err);