[gdk-pixbuf/gdk-pixbuf-2-40] Check the memset length argument

[Robert Ancell <rancell src gnome org>]

commit 43ec8f286e3d499d82735c16bbca83d7a1c03efa
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Wed Apr 1 18:11:55 2020 +0100

    Check the memset length argument
    
    Avoid overflows by using the checked multiplication macro for gsize.
    
    Fixes: #132

 gdk-pixbuf/io-gif-animation.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)
---
diff --git a/gdk-pixbuf/io-gif-animation.c b/gdk-pixbuf/io-gif-animation.c
index a3155e065..d74296337 100644
--- a/gdk-pixbuf/io-gif-animation.c
+++ b/gdk-pixbuf/io-gif-animation.c
@@ -411,11 +411,15 @@ gdk_pixbuf_gif_anim_iter_get_pixbuf (GdkPixbufAnimationIter *anim_iter)
 
         /* If no rendered frame, render the first frame */
         if (anim->last_frame == NULL) {
+                gsize len = 0;
                 if (anim->last_frame_data == NULL)
                         anim->last_frame_data = gdk_pixbuf_new (GDK_COLORSPACE_RGB, TRUE, 8, anim->width, 
anim->height);
                 if (anim->last_frame_data == NULL)
                         return NULL;
-                memset (gdk_pixbuf_get_pixels (anim->last_frame_data), 0, gdk_pixbuf_get_rowstride 
(anim->last_frame_data) * anim->height);
+                if (g_size_checked_mul (&len, gdk_pixbuf_get_rowstride (anim->last_frame_data), 
anim->height))
+                        memset (gdk_pixbuf_get_pixels (anim->last_frame_data), 0, len);
+                else
+                        return NULL;
                 composite_frame (anim, g_list_nth_data (anim->frames, 0));
         }