[gtk/gtk-3-24: 2/3] gtksettings: Avoid a possible NULL pointer dereference

[Matthias Clasen <matthiasc src gnome org>]

commit 33059211f43f775a24d1abbac70095198ff94ab7
Author: Olivier Fourdan <ofourdan redhat com>
Date:   Wed Sep 30 15:08:31 2020 +0200

    gtksettings: Avoid a possible NULL pointer dereference
    
    _gtk_settings_get_style_cascade() checks for the given GtkSettings to be
    non-NULL, but does so after using the pointer to get the
    GtkSettingsPrivate.
    
    Make sure we use the GtkSettings pointer only after the precondition is
    verified.
    
    https://gitlab.gnome.org/GNOME/gtk/-/issues/2780

 gtk/gtksettings.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)
---
diff --git a/gtk/gtksettings.c b/gtk/gtksettings.c
index 0f60dcdfe4..2e7c035705 100644
--- a/gtk/gtksettings.c
+++ b/gtk/gtksettings.c
@@ -1843,12 +1843,13 @@ GtkStyleCascade *
 _gtk_settings_get_style_cascade (GtkSettings *settings,
                                  gint         scale)
 {
-  GtkSettingsPrivate *priv = settings->priv;
+  GtkSettingsPrivate *priv;
   GtkStyleCascade *new_cascade;
   GSList *list;
 
   g_return_val_if_fail (GTK_IS_SETTINGS (settings), NULL);
 
+  priv = settings->priv;
   for (list = priv->style_cascades; list; list = list->next)
     {
       if (_gtk_style_cascade_get_scale (list->data) == scale)