wayland/activation: Don't grab if no serial or surface was provided

A client can create a token without any seat, serial, or surface. In
this case, we'd still try to grab, which would run into some unforseen
code paths, potentially resulting in the following crash:

  0) meta_wayland_tablet_seat_device_added (tablet_seat=0x55dff4271c90,
                                            device=0x7f87b80655b0) at
       ../src/wayland/meta-wayland-tablet-seat.c:200
  1) meta_wayland_tablet_seat_new (seat=0x0, manager=0x55dff3ec7b40) at
       ../src/wayland/meta-wayland-tablet-seat.c:283
  2) meta_wayland_tablet_manager_ensure_seat (manager=manager@entry=0x55dff3ec7b40,
                                              seat=seat@entry=0x0) at
       ../src/wayland/meta-wayland-tablet-manager.c:239
  3) meta_wayland_tablet_manager_ensure_seat (seat=0x0, manager=0x55dff3ec7b40) at
       ../src/wayland/meta-wayland-touch.c:595
  4) meta_wayland_seat_get_grab_info (seat=0x0, surface=0x55dff43ff5b0,
                                      serial=0, require_pressed=0, x=0x0, y=0x0) at
       ../src/wayland/meta-wayland-seat.c:479
  5) activation_activate (...) at
       ../src/wayland/meta-wayland-activation.c:261

Fix this by not trying to grab if not enough parameters was passed when
creating the token. Also add a test case that reproduces the above
crash.

Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/2081>

src/tests/wayland-test-clients/meson.build

@@ -51,6 +51,7 @@ wayland_test_clients = [
   'invalid-subsurfaces',
   'invalid-xdg-shell-actions',
   'xdg-apply-limits',
+  'xdg-activation',
 ]
 
 foreach test : wayland_test_clients

src/tests/wayland-test-clients/xdg-activation.c

@@ -0,0 +1,340 @@
+/*
+ * Copyright (C) 2021 Red Hat, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include "config.h"
+
+#include <glib.h>
+#include <sys/mman.h>
+#include <unistd.h>
+#include <wayland-client.h>
+
+#include "wayland-test-client-utils.h"
+
+#include "test-driver-client-protocol.h"
+#include "xdg-shell-client-protocol.h"
+#include "xdg-activation-v1-client-protocol.h"
+
+static struct wl_display *display;
+static struct wl_registry *registry;
+static struct wl_compositor *compositor;
+static struct xdg_wm_base *xdg_wm_base;
+static struct wl_seat *seat;
+static struct wl_shm *shm;
+static struct xdg_activation_v1 *activation;
+
+static struct wl_surface *surface;
+static struct xdg_surface *xdg_surface;
+static struct xdg_toplevel *xdg_toplevel;
+
+static gboolean running;
+
+static void
+init_surface (const char *token)
+{
+  xdg_toplevel_set_title (xdg_toplevel, "startup notification client");
+  xdg_activation_v1_activate (activation, token, surface);
+  wl_surface_commit (surface);
+}
+
+static void
+handle_buffer_release (void             *data,
+                       struct wl_buffer *buffer)
+{
+  wl_buffer_destroy (buffer);
+}
+
+static const struct wl_buffer_listener buffer_listener = {
+  handle_buffer_release
+};
+
+static gboolean
+create_shm_buffer (int                width,
+                   int                height,
+                   struct wl_buffer **out_buffer,
+                   void             **out_data,
+                   int               *out_size)
+{
+  struct wl_shm_pool *pool;
+  static struct wl_buffer *buffer;
+  int fd, size, stride;
+  int bytes_per_pixel;
+  void *data;
+
+  bytes_per_pixel = 4;
+  stride = width * bytes_per_pixel;
+  size = stride * height;
+
+  fd = create_anonymous_file (size);
+  if (fd < 0)
+    {
+      fprintf (stderr, "Creating a buffer file for %d B failed: %m\n",
+               size);
+      return FALSE;
+    }
+
+  data = mmap (NULL, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+  if (data == MAP_FAILED)
+    {
+      fprintf (stderr, "mmap failed: %m\n");
+      close (fd);
+      return FALSE;
+    }
+
+  pool = wl_shm_create_pool (shm, fd, size);
+  buffer = wl_shm_pool_create_buffer (pool, 0,
+                                      width, height,
+                                      stride,
+                                      WL_SHM_FORMAT_ARGB8888);
+  wl_buffer_add_listener (buffer, &buffer_listener, buffer);
+  wl_shm_pool_destroy (pool);
+  close (fd);
+
+  *out_buffer = buffer;
+  *out_data = data;
+  *out_size = size;
+
+  return TRUE;
+}
+
+static void
+fill (void    *buffer_data,
+      int      width,
+      int      height,
+      uint32_t color)
+{
+  uint32_t *pixels = buffer_data;
+  int x, y;
+
+  for (y = 0; y < height; y++)
+    {
+      for (x = 0; x < width; x++)
+        pixels[y * width + x] = color;
+    }
+}
+
+static void
+draw (struct wl_surface *surface,
+      int                width,
+      int                height,
+      uint32_t           color)
+{
+  struct wl_buffer *buffer;
+  void *buffer_data;
+  int size;
+
+  if (!create_shm_buffer (width, height,
+                          &buffer, &buffer_data, &size))
+    g_error ("Failed to create shm buffer");
+
+  fill (buffer_data, width, height, color);
+
+  wl_surface_attach (surface, buffer, 0, 0);
+}
+
+static void
+draw_main (void)
+{
+  draw (surface, 700, 500, 0xff00ff00);
+}
+
+static void
+handle_xdg_toplevel_configure (void                *data,
+                               struct xdg_toplevel *xdg_toplevel,
+                               int32_t              width,
+                               int32_t              height,
+                               struct wl_array     *state)
+{
+}
+
+static void
+handle_xdg_toplevel_close (void                *data,
+                           struct xdg_toplevel *xdg_toplevel)
+{
+  g_assert_not_reached ();
+}
+
+static const struct xdg_toplevel_listener xdg_toplevel_listener = {
+  handle_xdg_toplevel_configure,
+  handle_xdg_toplevel_close,
+};
+
+static void
+handle_xdg_surface_configure (void               *data,
+                              struct xdg_surface *xdg_surface,
+                              uint32_t            serial)
+{
+  draw_main ();
+  wl_surface_commit (surface);
+
+  g_assert_cmpint (wl_display_roundtrip (display), !=, -1);
+  running = FALSE;
+}
+
+static const struct xdg_surface_listener xdg_surface_listener = {
+  handle_xdg_surface_configure,
+};
+
+static void
+handle_xdg_wm_base_ping (void               *data,
+                         struct xdg_wm_base *xdg_wm_base,
+                         uint32_t            serial)
+{
+  xdg_wm_base_pong (xdg_wm_base, serial);
+}
+
+static const struct xdg_wm_base_listener xdg_wm_base_listener = {
+  handle_xdg_wm_base_ping,
+};
+
+static void
+handle_registry_global (void               *data,
+                        struct wl_registry *registry,
+                        uint32_t            id,
+                        const char         *interface,
+                        uint32_t            version)
+{
+  if (strcmp (interface, "wl_compositor") == 0)
+    {
+      compositor = wl_registry_bind (registry, id, &wl_compositor_interface, 1);
+    }
+  else if (strcmp (interface, "xdg_wm_base") == 0)
+    {
+      xdg_wm_base = wl_registry_bind (registry, id,
+                                      &xdg_wm_base_interface, 1);
+      xdg_wm_base_add_listener (xdg_wm_base, &xdg_wm_base_listener, NULL);
+    }
+  else if (strcmp (interface, "wl_seat") == 0)
+    {
+      seat = wl_registry_bind (registry,
+                               id, &wl_seat_interface, 1);
+    }
+  else if (strcmp (interface, "wl_shm") == 0)
+    {
+      shm = wl_registry_bind (registry,
+                              id, &wl_shm_interface, 1);
+    }
+  else if (strcmp (interface, "xdg_activation_v1") == 0)
+    {
+      activation = wl_registry_bind (registry,
+                                     id, &xdg_activation_v1_interface, 1);
+    }
+}
+
+static void
+handle_registry_global_remove (void               *data,
+                               struct wl_registry *registry,
+                               uint32_t            name)
+{
+}
+
+static const struct wl_registry_listener registry_listener = {
+  handle_registry_global,
+  handle_registry_global_remove
+};
+
+static void
+token_done (gpointer                        user_data,
+            struct xdg_activation_token_v1 *provider,
+            const char                     *token)
+{
+  char **token_ptr = user_data;
+
+  *token_ptr = g_strdup (token);
+}
+
+static const struct xdg_activation_token_v1_listener token_listener = {
+  token_done,
+};
+
+static char *
+get_token (void)
+{
+  struct xdg_activation_token_v1 *token;
+  char *token_string = NULL;
+
+  token = xdg_activation_v1_get_activation_token (activation);
+
+  xdg_activation_token_v1_add_listener (token,
+                                        &token_listener,
+                                        &token_string);
+  xdg_activation_token_v1_commit (token);
+
+  while (!token_string)
+    {
+      if (wl_display_roundtrip (display) == -1)
+        break;
+    }
+  xdg_activation_token_v1_destroy (token);
+
+  return token_string;
+}
+
+static void
+test_startup_notifications (void)
+{
+  g_autofree char *token = NULL;
+
+  display = wl_display_connect (NULL);
+  registry = wl_display_get_registry (display);
+  wl_registry_add_listener (registry, &registry_listener, NULL);
+  wl_display_roundtrip (display);
+
+  g_assert_nonnull (shm);
+  g_assert_nonnull (seat);
+  g_assert_nonnull (xdg_wm_base);
+  g_assert_nonnull (activation);
+
+  wl_display_roundtrip (display);
+
+  token = get_token ();
+
+  surface = wl_compositor_create_surface (compositor);
+  xdg_surface = xdg_wm_base_get_xdg_surface (xdg_wm_base, surface);
+  xdg_surface_add_listener (xdg_surface, &xdg_surface_listener, NULL);
+  xdg_toplevel = xdg_surface_get_toplevel (xdg_surface);
+  xdg_toplevel_add_listener (xdg_toplevel, &xdg_toplevel_listener, NULL);
+
+  init_surface (token);
+
+  running = TRUE;
+  while (running)
+    {
+      if (wl_display_dispatch (display) == -1)
+        return;
+    }
+
+  wl_display_roundtrip (display);
+
+  g_clear_pointer (&xdg_toplevel, xdg_toplevel_destroy);
+  g_clear_pointer (&xdg_surface, xdg_surface_destroy);
+  g_clear_pointer (&xdg_wm_base, xdg_wm_base_destroy);
+  g_clear_pointer (&activation, xdg_activation_v1_destroy);
+  g_clear_pointer (&compositor, wl_compositor_destroy);
+  g_clear_pointer (&seat, wl_seat_destroy);
+  g_clear_pointer (&shm, wl_shm_destroy);
+  g_clear_pointer (&registry, wl_registry_destroy);
+  g_clear_pointer (&display, wl_display_disconnect);
+}
+
+int
+main (int    argc,
+      char **argv)
+{
+  test_startup_notifications ();
+
+  return EXIT_SUCCESS;
+}

src/tests/wayland-unit-tests.c

@@ -247,6 +247,17 @@ toplevel_apply_limits (void)
   g_test_assert_expected_messages ();
 }
 
+static void
+toplevel_activation (void)
+{
+  ApplyLimitData data = {};
+
+  data.loop = g_main_loop_new (NULL, FALSE);
+  data.wayland_test_client = wayland_test_client_new ("xdg-activation");
+  wayland_test_client_finish (data.wayland_test_client);
+  g_test_assert_expected_messages ();
+}
+
 static void
 pre_run_wayland_tests (void)
 {
@@ -271,6 +282,8 @@ init_wayland_tests (void)
                    subsurface_invalid_xdg_shell_actions);
   g_test_add_func ("/wayland/toplevel/apply-limits",
                    toplevel_apply_limits);
+  g_test_add_func ("/wayland/toplevel/activation",
+                   toplevel_activation);
 }
 
 int

src/wayland/meta-wayland-activation.c

@@ -278,7 +278,9 @@ activation_activate (struct wl_client   *client,
   if (!token)
     return;
 
-  if (meta_wayland_seat_get_grab_info (token->seat,
+  if (token->seat &&
+      token->surface &&
+      meta_wayland_seat_get_grab_info (token->seat,
                                        token->surface,
                                        token->serial,
                                        FALSE, NULL, NULL))