From 8af1cfac332f6f7c4e6db40c851dd5ac719236f1 Mon Sep 17 00:00:00 2001
From: Harald Sitter <sitter@kde.org>
Date: Mon, 17 Apr 2023 16:01:50 +0200
Subject: [PATCH] don't stumble over nullptrs if outputs changed during saving

exec() opens a nested eventloop that does event processing and may end
up processing output changes when e.g. a screen is getting unplugged. as
part of this our m_configHandler may get reset to null, so make sure the
pointers are still valid after exec

BUG: 466960


(cherry picked from commit 0bfa16bd2b59ac9b2ce8112c06d86e5e29c69654)
---
 kcm/kcm.cpp | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/kcm/kcm.cpp b/kcm/kcm.cpp
index f292699c..931509eb 100644
--- a/kcm/kcm.cpp
+++ b/kcm/kcm.cpp
@@ -172,6 +172,13 @@ void KCMKScreen::doSave()
     m_stopUpdatesFromBackend = true;
     op->exec();
 
+    // exec() opens a nested eventloop that may have unset m_configHandler if (e.g.)
+    // outputs changed during saving. https://bugs.kde.org/show_bug.cgi?id=466960
+    if (!m_configHandler || !m_configHandler->config()) {
+        Q_EMIT errorOnSave();
+        return;
+    }
+
     const auto updateInitialData = [this]() {
         if (!m_configHandler || !m_configHandler->config()) {
             return;
-- 
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