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window: check for possible loop in transients

If a broken or naughty application tries set up its windows to create
a loop in the transient relationship, mutter will hang, looping forever
in meta_window_foreach_ancestor()

To avoid looping infinitely at various point in the code, check for a
possible loop when setting the transient relationship and deny the
request to set a window transient for another if that would create a
loop.

Bugzilla: https://bugzilla.gnome.org/show_bug.cgi?id=759299
This commit is contained in:
Olivier Fourdan 2015-12-15 16:55:29 +01:00
parent acd50508dc
commit 4e82a751fb

View file

@ -7388,10 +7388,31 @@ meta_window_set_gtk_dbus_properties (MetaWindow *window,
g_object_thaw_notify (G_OBJECT (window));
}
static gboolean
check_transient_for_loop (MetaWindow *window,
MetaWindow *parent)
{
while (parent)
{
if (parent->transient_for == window)
return TRUE;
parent = parent->transient_for;
}
return FALSE;
}
void
meta_window_set_transient_for (MetaWindow *window,
MetaWindow *parent)
{
if (check_transient_for_loop (window, parent))
{
meta_warning ("Setting %s transient for %s would create a loop.\n",
window->desc, parent->desc);
return;
}
if (meta_window_appears_focused (window) && window->transient_for != NULL)
meta_window_propagate_focus_appearance (window, FALSE);