From 439e19be17b9169f5786b2593e6d1ac6978bb84b Mon Sep 17 00:00:00 2001
From: Liang Qi <liang.qi@qt.io>
Date: Mon, 16 Sep 2024 11:14:15 +0200
Subject: [PATCH] xcb: check validity of RandR output info before using it
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Fixes: QTBUG-128906
Pick-to: 6.8 6.7 6.5 6.2 5.15
Change-Id: Ibafdf4bb9c449b29437b0520299ab407238e5703
Reviewed-by: Tor Arne Vestbø <tor.arne.vestbo@qt.io>
---
 src/plugins/platforms/xcb/qxcbconnection_screens.cpp | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/plugins/platforms/xcb/qxcbconnection_screens.cpp b/src/plugins/platforms/xcb/qxcbconnection_screens.cpp
index c31e9b10390..3dbb8835422 100644
--- a/src/plugins/platforms/xcb/qxcbconnection_screens.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection_screens.cpp
@@ -140,7 +140,7 @@ void QXcbConnection::updateScreens(const xcb_randr_notify_event_t *event)
                 // Screen has been disabled
                 auto outputInfo = Q_XCB_REPLY(xcb_randr_get_output_info, xcb_connection(),
                                               output.output, output.config_timestamp);
-                if (outputInfo->crtc == XCB_NONE) {
+                if (!outputInfo || outputInfo->crtc == XCB_NONE) {
                     qCDebug(lcQpaScreen) << "output" << screen->name() << "has been disabled";
                     destroyScreen(screen);
                 } else {