[mutter] cogl/texture-2d-sliced: Don't double-free slice array when alloc failed

[Marge Bot <marge-bot src gnome org>]

commit 96842fc570b5e244d6614949b8a208ac084efb1e
Author: Jonas Ådahl <jadahl gmail com>
Date:   Fri Dec 18 11:24:32 2020 +0100

    cogl/texture-2d-sliced: Don't double-free slice array when alloc failed
    
    If texture allocation failed for a sliced 2D texture, the alloc()
    function would free the slices immediately, but not clear the pointer to
    the slices array. When the code attempting to allocate the texture then
    freed the texture object, the cleanup functions tried to free the slices
    array again, since it wasn't NULL.
    
    Fix this by clearing the slices array after freeing it.
    
    Closes: https://gitlab.gnome.org/GNOME/mutter/-/issues/1580
    Part-of: <https://gitlab.gnome.org/GNOME/mutter/-/merge_requests/1648>

 cogl/cogl/cogl-texture-2d-sliced.c | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/cogl/cogl/cogl-texture-2d-sliced.c b/cogl/cogl/cogl-texture-2d-sliced.c
index 2d903e83b2..8e7f91f703 100644
--- a/cogl/cogl/cogl-texture-2d-sliced.c
+++ b/cogl/cogl/cogl-texture-2d-sliced.c
@@ -760,6 +760,7 @@ free_slices (CoglTexture2DSliced *tex_2ds)
         }
 
       g_array_free (tex_2ds->slice_textures, TRUE);
+      tex_2ds->slice_textures = NULL;
     }
 
   free_spans (tex_2ds);