From b0a09ba6020147961acc62d9c73d807b4cccd9f7 Mon Sep 17 00:00:00 2001
From: Peter Hutterer <peter.hutterer@who-t.net>
Date: Wed, 4 Dec 2024 15:49:43 +1000
Subject: [PATCH] dix: keep a ref to the rootCursor

CreateCursor returns a cursor with refcount 1 - that refcount is used by
the resource system, any caller needs to call RefCursor to get their own
reference. That happens correctly for normal cursors but for our
rootCursor we keep a variable to the cursor despite not having a ref for
ourselves.

Fix this by reffing/unreffing the rootCursor to ensure our pointer is
valid.

Related to CVE-2025-26594, ZDI-CAN-25544

Reviewed-by: Olivier Fourdan <ofourdan@redhat.com>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1828>
---
 dix/main.c | 4 ++++
 1 file changed, 4 insertions(+)


--- ./dix/main.c.orig	2021-12-15 13:01:24.000000000 -0600
+++ ./dix/main.c	2025-02-25 13:24:51.377731931 -0600
@@ -235,6 +235,8 @@
                        defaultCursorFont);
         }
 
+        rootCursor = RefCursor(rootCursor);
+
 #ifdef PANORAMIX
         /*
          * Consolidate window and colourmap information for each screen
@@ -275,6 +277,8 @@
 
         Dispatch();
 
+        UnrefCursor(rootCursor);
+
         UndisplayDevices();
         DisableAllDevices();