From 8d82263513805ba30a3d8ee45ed32f88a6610e1d Mon Sep 17 00:00:00 2001
From: PatTheMav <PatTheMav@users.noreply.github.com>
Date: Mon, 14 Aug 2023 18:09:05 +0200
Subject: [PATCH] UI: Fix possible race condition in DrawSpacingHelpers

The use of GetCurrentSceneItem can lead to a race condition between
the graphics thread (where this function will be run) and the main UI
thread, as both access the scene list model and iterate through its
members which can change during iteration (as there is no lock around
its access).
---
 UI/window-basic-preview.cpp | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/UI/window-basic-preview.cpp b/UI/window-basic-preview.cpp
index d3c9e4e55..48317ee13 100644
--- a/UI/window-basic-preview.cpp
+++ b/UI/window-basic-preview.cpp
@@ -2461,10 +2461,10 @@ void OBSBasicPreview::DrawSpacingHelpers()
 
 	obs_scene_enum_items(main->GetCurrentScene(), FindSelected, &data);
 
-	if (data.sceneItems.size() > 1)
+	if (data.sceneItems.size() != 1)
 		return;
 
-	OBSSceneItem item = main->GetCurrentSceneItem();
+	OBSSceneItem item = data.sceneItems[0];
 	if (!item)
 		return;