[plasma/kwin] src/wayland: wayland: use QPointer for the xdg_popup parent surface

Git commit 72e9cb50465971bda64ee39d06aa18e8cedaf0d5 by Vlad Zahorodnii, on behalf of zhang shoucheng.
Committed on 10/08/2026 at 09:32.
Pushed by vladz into branch 'master'.

wayland: use QPointer for the xdg_popup parent surface

This is a defensive fix. parentSurface was a raw pointer that was
never cleared. Normally the popup is destroyed before its parent
surface, but an abnormal or malicious client can destroy the parent
wl_surface first and then send xdg_popup.reposition, which would
dereference the freed pointer. Use a QPointer so the pointer is
automatically nulled when the parent surface is destroyed.

M  +2    -1    src/wayland/xdgshell_p.h

https://invent.kde.org/plasma/kwin/-/commit/72e9cb50465971bda64ee39d06aa18e8cedaf0d5

diff --git a/src/wayland/xdgshell_p.h b/src/wayland/xdgshell_p.h
index 0fdd5041cdd..6f47eba8b1b 100644
--- a/src/wayland/xdgshell_p.h
+++ b/src/wayland/xdgshell_p.h
@@ -7,6 +7,7 @@
 #pragma once
 
 #include <QIcon>
+#include <QPointer>
 
 #include "qwayland-server-xdg-shell.h"
 #include "xdgshell.h"
@@ -194,7 +195,7 @@ public:
     void reset();
 
     XdgPopupInterface *q;
-    SurfaceInterface *parentSurface = nullptr;
+    QPointer<SurfaceInterface> parentSurface;
     XdgSurfaceInterface *xdgSurface;
     XdgPositioner positioner;