[glib: 9/11] xdgmime: Prevent infinite loops from badly-formed MIME registrations

[Philip Withnall <pwithnall src gnome org>]

commit 38869ece243068f3e76d160837bdac5d437325d4
Author: Philip Withnall <withnall endlessm com>
Date:   Mon Sep 2 18:02:05 2019 +0100

    xdgmime: Prevent infinite loops from badly-formed MIME registrations
    
    Signed-off-by: Philip Withnall <withnall endlessm com>
    
    Closes: #1875

 gio/xdgmime/xdgmimecache.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/gio/xdgmime/xdgmimecache.c b/gio/xdgmime/xdgmimecache.c
index 2f519a43a..3818180ae 100644
--- a/gio/xdgmime/xdgmimecache.c
+++ b/gio/xdgmime/xdgmimecache.c
@@ -966,7 +966,9 @@ _xdg_mime_cache_mime_type_subclass (const char *mime,
              for (j = 0; j < n_parents; j++)
                {
                  parent_offset = GET_UINT32 (cache->buffer, offset + 4 + 4 * j);
-                 if (_xdg_mime_cache_mime_type_subclass (cache->buffer + parent_offset, ubase))
+                 if (strcmp (cache->buffer + parent_offset, mime) != 0 &&
+                     strcmp (cache->buffer + parent_offset, umime) != 0 &&
+                     _xdg_mime_cache_mime_type_subclass (cache->buffer + parent_offset, ubase))
                    return 1;
                }