From 797f63b8be1693a7c0ae5df8b76911d804959ce5 Mon Sep 17 00:00:00 2001
From: Peter Hutterer <peter.hutterer@who-t.net>
Date: Thu, 6 Mar 2025 09:40:22 +1000
Subject: [PATCH] Xi: disallow grabbing disabled devices

Grabbing a disabled (pointer) device will lead to a segfault later
in the myriad of places where we look at the device's spriteInfo - which
will be NULL.

As a workaround, disallow grabbing a disabled device by pretending it's
already grabbed. Since the point of a grab is to receive all events by
that device and disabled devices cannot send events, this should be Good
Enough.

Tested-by: Olivier Fourdan <ofourdan@redhat.com>
Part-of: <https://gitlab.freedesktop.org/xorg/xserver/-/merge_requests/1856>
---
 Xi/xigrabdev.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/Xi/xigrabdev.c b/Xi/xigrabdev.c
index 0ea42db88..f7fea9cf3 100644
--- a/Xi/xigrabdev.c
+++ b/Xi/xigrabdev.c
@@ -81,6 +81,9 @@ ProcXIGrabDevice(ClientPtr client)
     if (ret != Success)
         return ret;
 
+    if (!dev->enabled)
+        return AlreadyGrabbed;
+
     if (!IsMaster(dev))
         stuff->paired_device_mode = GrabModeAsync;