File 0001-wayland-Fix-crash-in-QWaylandShmBackingStore-scroll.patch of Package qt6-base

From c93008e4d06abb0072e0e5e57d84a4ae182ecfc0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?B=C5=82a=C5=BCej=20Szczygie=C5=82?= <mumei6102@gmail.com>
Date: Tue, 21 Oct 2025 19:49:17 +0200
Subject: [PATCH] wayland: Fix crash in QWaylandShmBackingStore::scroll()

Fixes a crash when monitor is unplugged while scrolling.

recreateBackBufferIfNeeded() calls getBuffer() which may set
mFrontBuffer to nullptr.

Amends: 6f25f703fd37a900c139e14a33a4639502bfeae7

Task-number: QTBUG-139231
Change-Id: Ia5bedce2a3f6580c722f73446de81a26d40ea2f4
Reviewed-by: David Edmundson <davidedmundson@kde.org>
---
 src/plugins/platforms/wayland/qwaylandshmbackingstore.cpp | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/plugins/platforms/wayland/qwaylandshmbackingstore.cpp b/src/plugins/platforms/wayland/qwaylandshmbackingstore.cpp
index b853db21529..fa70b53cbd0 100644
--- a/src/plugins/platforms/wayland/qwaylandshmbackingstore.cpp
+++ b/src/plugins/platforms/wayland/qwaylandshmbackingstore.cpp
@@ -229,7 +229,7 @@ void QWaylandShmBackingStore::endPaint()
 // Inspired by QCALayerBackingStore.
 bool QWaylandShmBackingStore::scroll(const QRegion &region, int dx, int dy)
 {
-    if (Q_UNLIKELY(!mBackBuffer || !mFrontBuffer))
+    if (Q_UNLIKELY(!mBackBuffer))
         return false;
 
     const qreal devicePixelRatio = waylandWindow()->scale();
@@ -241,6 +241,8 @@ bool QWaylandShmBackingStore::scroll(const QRegion &region, int dx, int dy)
         return false;
 
     recreateBackBufferIfNeeded();
+    if (!mFrontBuffer)
+        return false;
 
     const QPoint scrollDelta(dx, dy);
     const QMargins margins = windowDecorationMargins();
-- 
2.52.0