Update from debian/bullseye-security for apertis/v2023-security

debian/patches/Xi-do-not-keep-linked-list-pointer-during-recursion.patch

+From 4e0e99ef60f07757756913221847a26c71afc3e8 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Jos=C3=A9=20Exp=C3=B3sito?= <jexposit@redhat.com>
+Date: Fri, 22 Dec 2023 18:28:31 +0100
+Subject: [PATCH] Xi: do not keep linked list pointer during recursion
+
+The `DisableDevice()` function is called whenever an enabled device
+is disabled and it moves the device from the `inputInfo.devices` linked
+list to the `inputInfo.off_devices` linked list.
+
+However, its link/unlink operation has an issue during the recursive
+call to `DisableDevice()` due to the `prev` pointer pointing to a
+removed device.
+
+This issue leads to a length mismatch between the total number of
+devices and the number of device in the list, leading to a heap
+overflow and, possibly, to local privilege escalation.
+
+Simplify the code that checked whether the device passed to
+`DisableDevice()` was in `inputInfo.devices` or not and find the
+previous device after the recursion.
+
+CVE-2024-21886, ZDI-CAN-22840
+
+This vulnerability was discovered by:
+Jan-Niklas Sohn working with Trend Micro Zero Day Initiative
+---
+ dix/devices.c | 15 ++++++++++++---
+ 1 file changed, 12 insertions(+), 3 deletions(-)
+
+diff --git a/dix/devices.c b/dix/devices.c
+index 3f3224d62..3a64d8702 100644
+--- a/dix/devices.c
++++ b/dix/devices.c
+@@ -451,14 +451,20 @@ DisableDevice(DeviceIntPtr dev, BOOL sendevent)
+ {
+     DeviceIntPtr *prev, other;
+     BOOL enabled;
++    BOOL dev_in_devices_list = FALSE;
+     int flags[MAXDEVICES] = { 0 };
+ 
+     if (!dev->enabled)
+         return TRUE;
+ 
+-    for (prev = &inputInfo.devices;
+-         *prev && (*prev != dev); prev = &(*prev)->next);
+-    if (*prev != dev)
++    for (other = inputInfo.devices; other; other = other->next) {
++        if (other == dev) {
++            dev_in_devices_list = TRUE;
++            break;
++        }
++    }
++
++    if (!dev_in_devices_list)
+         return FALSE;
+ 
+     TouchEndPhysicallyActiveTouches(dev);
+@@ -509,6 +515,9 @@ DisableDevice(DeviceIntPtr dev, BOOL sendevent)
+     LeaveWindow(dev);
+     SetFocusOut(dev);
+ 
++    for (prev = &inputInfo.devices;
++         *prev && (*prev != dev); prev = &(*prev)->next);
++
+     *prev = dev->next;
+     dev->next = inputInfo.off_devices;
+     inputInfo.off_devices = dev;
+-- 
+2.43.0
+