From b42919e875589f643857c7251ca7aa7221bf38f0 Mon Sep 17 00:00:00 2001
From: Vlad Zahorodnii <vlad.zahorodnii@kde.org>
Date: Fri, 26 May 2023 14:29:53 +0300
Subject: [PATCH] Add closed window checks in restacking requests

If a closed window is restacked, it will be reintroduced to the stack
and it will be left dangling, which will eventually result in a crash.
---
 src/layers.cpp | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/src/layers.cpp b/src/layers.cpp
index efa4391356..1c3453a29d 100644
--- a/src/layers.cpp
+++ b/src/layers.cpp
@@ -293,6 +293,10 @@ void Workspace::lowerWindow(Window *window, bool nogroup)
     if (!window) {
         return;
     }
+    if (window->isDeleted()) {
+        qCWarning(KWIN_CORE) << "Workspace::lowerWindow: closed window" << window << "cannot be restacked";
+        return;
+    }
 
     window->cancelAutoRaise();
 
@@ -319,6 +323,10 @@ void Workspace::lowerWindowWithinApplication(Window *window)
     if (!window) {
         return;
     }
+    if (window->isDeleted()) {
+        qCWarning(KWIN_CORE) << "Workspace::lowerWindowWithinApplication: closed window" << window << "cannot be restacked";
+        return;
+    }
 
     window->cancelAutoRaise();
 
@@ -349,6 +357,10 @@ void Workspace::raiseWindow(Window *window, bool nogroup)
     if (!window) {
         return;
     }
+    if (window->isDeleted()) {
+        qCWarning(KWIN_CORE) << "Workspace::raiseWindow: closed window" << window << "cannot be restacked";
+        return;
+    }
 
     window->cancelAutoRaise();
 
@@ -374,6 +386,10 @@ void Workspace::raiseWindowWithinApplication(Window *window)
     if (!window) {
         return;
     }
+    if (window->isDeleted()) {
+        qCWarning(KWIN_CORE) << "Workspace::raiseWindowWithinApplication: closed window" << window << "cannot be restacked";
+        return;
+    }
 
     window->cancelAutoRaise();
 
@@ -427,6 +443,10 @@ void Workspace::lowerWindowRequest(Window *window)
 
 void Workspace::restack(Window *window, Window *under, bool force)
 {
+    if (window->isDeleted()) {
+        qCWarning(KWIN_CORE) << "Workspace::restack: closed window" << window << "cannot be restacked";
+        return;
+    }
     Q_ASSERT(unconstrained_stacking_order.contains(under));
     if (!force && !Window::belongToSameApplication(under, window)) {
         // put in the stacking order below _all_ windows belonging to the active application