Copied from Fedora.

http://pkgs.fedoraproject.org/cgit/libwmf.git/tree/libwmf-0.2.8.4-CAN-2004-0941.patch

--- libwmf-0.2.8.4/src/extra/gd/gd_png.c	2004-11-11 14:02:37.407589824 -0500
+++ libwmf-0.2.8.4/src/extra/gd/gd_png.c	2004-11-11 14:04:29.672522960 -0500
@@ -188,6 +188,14 @@
 
   png_get_IHDR (png_ptr, info_ptr, &width, &height, &bit_depth, &color_type,
 		&interlace_type, NULL, NULL);
+  if (overflow2(sizeof (int), width)) 
+    {
+      return NULL;
+    }
+  if (overflow2(sizeof (int) * width, height)) 
+    {
+      return NULL;
+    }  
   if ((color_type == PNG_COLOR_TYPE_RGB) ||
       (color_type == PNG_COLOR_TYPE_RGB_ALPHA))
     {
