[pango/attr-list-bad-access] AVoid a use-after-free in pango_attr_list_change

[Matthias Clasen <matthiasc src gnome org>]

commit b545363bdc94f82b7d7208da7a7a2a7cb026981f
Author: Matthias Clasen <mclasen redhat com>
Date:   Wed Mar 16 15:46:51 2022 -0400

    AVoid a use-after-free in pango_attr_list_change
    
    This was showing up as crashes in pitivi and inkscape.
    
    Fixes: #678

 pango/pango-attributes.c | 3 +++
 1 file changed, 3 insertions(+)
---
diff --git a/pango/pango-attributes.c b/pango/pango-attributes.c
index 60d14706..3a56f581 100644
--- a/pango/pango-attributes.c
+++ b/pango/pango-attributes.c
@@ -2157,6 +2157,9 @@ pango_attr_list_change (PangoAttrList  *list,
       if (tmp_attr->klass->type != attr->klass->type)
         continue;
 
+      if (tmp_attr == attr)
+        continue;
+
       if (tmp_attr->end_index <= attr->end_index ||
           pango_attribute_equal (tmp_attr, attr))
         {