From bd4062a196b15849b80fb76a9e5217f2b992ffb5 Mon Sep 17 00:00:00 2001
From: Carlos Garnacho <carlosg@gnome.org>
Date: Thu, 22 Oct 2020 11:18:34 +0200
Subject: [PATCH] clutter: Limit number of touch slots available to a virtual
 touch device

It's not worth letting these devices have an "unlimited" range of touch
slots. Limiting it to 32 is more than enough to map it with real touch
devices nowadays.

https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1486
---
 .../clutter/clutter-virtual-input-device.c    | 12 ++++++++
 .../clutter/clutter-virtual-input-device.h    |  2 ++
 src/backends/meta-remote-desktop-session.c    | 28 +++++++++++++++++--
 3 files changed, 40 insertions(+), 2 deletions(-)

diff --git a/clutter/clutter/clutter-virtual-input-device.c b/clutter/clutter/clutter-virtual-input-device.c
index 522a6596f..ff733a464 100644
--- a/clutter/clutter/clutter-virtual-input-device.c
+++ b/clutter/clutter/clutter-virtual-input-device.c
@@ -151,6 +151,10 @@ clutter_virtual_input_device_notify_touch_down (ClutterVirtualInputDevice *virtu
   ClutterVirtualInputDeviceClass *klass =
     CLUTTER_VIRTUAL_INPUT_DEVICE_GET_CLASS (virtual_device);
 
+  g_return_if_fail (CLUTTER_IS_VIRTUAL_INPUT_DEVICE (virtual_device));
+  g_return_if_fail (slot >= 0 &&
+                    slot < CLUTTER_VIRTUAL_INPUT_DEVICE_MAX_TOUCH_SLOTS);
+
   klass->notify_touch_down (virtual_device, time_us,
                             slot, x, y);
 }
@@ -165,6 +169,10 @@ clutter_virtual_input_device_notify_touch_motion (ClutterVirtualInputDevice *vir
   ClutterVirtualInputDeviceClass *klass =
     CLUTTER_VIRTUAL_INPUT_DEVICE_GET_CLASS (virtual_device);
 
+  g_return_if_fail (CLUTTER_IS_VIRTUAL_INPUT_DEVICE (virtual_device));
+  g_return_if_fail (slot >= 0 &&
+                    slot < CLUTTER_VIRTUAL_INPUT_DEVICE_MAX_TOUCH_SLOTS);
+
   klass->notify_touch_motion (virtual_device, time_us,
                               slot, x, y);
 }
@@ -177,6 +185,10 @@ clutter_virtual_input_device_notify_touch_up (ClutterVirtualInputDevice *virtual
   ClutterVirtualInputDeviceClass *klass =
     CLUTTER_VIRTUAL_INPUT_DEVICE_GET_CLASS (virtual_device);
 
+  g_return_if_fail (CLUTTER_IS_VIRTUAL_INPUT_DEVICE (virtual_device));
+  g_return_if_fail (slot >= 0 &&
+                    slot < CLUTTER_VIRTUAL_INPUT_DEVICE_MAX_TOUCH_SLOTS);
+
   klass->notify_touch_up (virtual_device, time_us,
                           slot);
 }
diff --git a/clutter/clutter/clutter-virtual-input-device.h b/clutter/clutter/clutter-virtual-input-device.h
index b829c04ad..fb357af1e 100644
--- a/clutter/clutter/clutter-virtual-input-device.h
+++ b/clutter/clutter/clutter-virtual-input-device.h
@@ -31,6 +31,8 @@
 
 #define CLUTTER_TYPE_VIRTUAL_INPUT_DEVICE (clutter_virtual_input_device_get_type ())
 
+#define CLUTTER_VIRTUAL_INPUT_DEVICE_MAX_TOUCH_SLOTS 32u
+
 CLUTTER_EXPORT
 G_DECLARE_DERIVABLE_TYPE (ClutterVirtualInputDevice,
                           clutter_virtual_input_device,
diff --git a/src/backends/meta-remote-desktop-session.c b/src/backends/meta-remote-desktop-session.c
index 28191a1e0..27bd58b72 100644
--- a/src/backends/meta-remote-desktop-session.c
+++ b/src/backends/meta-remote-desktop-session.c
@@ -629,6 +629,14 @@ handle_notify_touch_down (MetaDBusRemoteDesktopSession *skeleton,
   if (!meta_remote_desktop_session_check_can_notify (session, invocation))
     return TRUE;
 
+  if (slot > CLUTTER_VIRTUAL_INPUT_DEVICE_MAX_TOUCH_SLOTS)
+    {
+      g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
+                                             G_DBUS_ERROR_FAILED,
+                                             "Touch slot out of range");
+      return TRUE;
+    }
+
   if (!session->screen_cast_session)
     {
       g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
@@ -676,6 +684,14 @@ handle_notify_touch_motion (MetaDBusRemoteDesktopSession *skeleton,
     return TRUE;
 
 
+  if (slot > CLUTTER_VIRTUAL_INPUT_DEVICE_MAX_TOUCH_SLOTS)
+    {
+      g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
+                                             G_DBUS_ERROR_FAILED,
+                                             "Touch slot out of range");
+      return TRUE;
+    }
+
   if (!session->screen_cast_session)
     {
       g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
@@ -709,14 +725,22 @@ handle_notify_touch_motion (MetaDBusRemoteDesktopSession *skeleton,
 
 static gboolean
 handle_notify_touch_up (MetaDBusRemoteDesktopSession *skeleton,
-                          GDBusMethodInvocation        *invocation,
-                          unsigned int                  slot)
+                        GDBusMethodInvocation        *invocation,
+                        unsigned int                  slot)
 {
   MetaRemoteDesktopSession *session = META_REMOTE_DESKTOP_SESSION (skeleton);
 
   if (!meta_remote_desktop_session_check_can_notify (session, invocation))
     return TRUE;
 
+  if (slot > CLUTTER_VIRTUAL_INPUT_DEVICE_MAX_TOUCH_SLOTS)
+    {
+      g_dbus_method_invocation_return_error (invocation, G_DBUS_ERROR,
+                                             G_DBUS_ERROR_FAILED,
+                                             "Touch slot out of range");
+      return TRUE;
+    }
+
   clutter_virtual_input_device_notify_touch_up (session->virtual_touchscreen,
                                                        CLUTTER_CURRENT_TIME,
                                                        slot);