[gtk/wip/carlosg/tablet-disconnects] gdk/wayland: Handle disorderly tablet/pad disconnects

[Carlos Garnacho <carlosg src gnome org>]

commit 948782b7e58a4ac923bf69f2f6f20893dcd4bf6f
Author: Carlos Garnacho <carlosg gnome org>
Date:   Fri May 15 18:39:57 2020 +0200

    gdk/wayland: Handle disorderly tablet/pad disconnects
    
    If the tablet gets removed/freed while there are pad events in flight,
    we leave a dangling pointer from the pad to the tablet, which may
    lead to invalid reads/writes when handling the pad event(s).
    
    Fixes: https://gitlab.gnome.org/GNOME/gtk/-/issues/2748

 gdk/wayland/gdkdevice-wayland.c | 8 ++++++++
 1 file changed, 8 insertions(+)
---
diff --git a/gdk/wayland/gdkdevice-wayland.c b/gdk/wayland/gdkdevice-wayland.c
index 6b8529d872..7d81eaff3b 100644
--- a/gdk/wayland/gdkdevice-wayland.c
+++ b/gdk/wayland/gdkdevice-wayland.c
@@ -2816,6 +2816,14 @@ _gdk_wayland_seat_remove_tablet (GdkWaylandSeat       *seat,
 
   zwp_tablet_v2_destroy (tablet->wp_tablet);
 
+  while (tablet->pads)
+    {
+      GdkWaylandTabletPadData *pad = tablet->pads->data;
+
+      pad->current_tablet = NULL;
+      tablet->pads = g_list_remove (tablet->pads, pad);
+    }
+
   device_manager->devices =
     g_list_remove (device_manager->devices, tablet->master);
   device_manager->devices =