From f1f80bbaa2ee501667f90ab31c00f3b9c31e7a95 Mon Sep 17 00:00:00 2001
From: Cristy <urban-warrior@imagemagick.org>
Date: Fri, 22 Sep 2017 09:15:49 -0400
Subject: [PATCH] https://github.com/ImageMagick/ImageMagick/issues/773

---
 coders/png.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/coders/png.c b/coders/png.c
index d93193407..d3027c850 100644
--- a/coders/png.c
+++ b/coders/png.c
@@ -4339,22 +4339,22 @@ DestroyJNG(unsigned char *chunk,Image **color_image,
   ImageInfo **alpha_image_info)
 {
   (void) RelinquishMagickMemory(chunk);
-  if (*color_image_info)
+  if (color_image_info && *color_image_info)
   {
     DestroyImageInfo(*color_image_info);
     *color_image_info = (ImageInfo *)NULL;
   }
-  if (*alpha_image_info)
+  if (alpha_image_info && *alpha_image_info)
   {
     DestroyImageInfo(*alpha_image_info);
     *alpha_image_info = (ImageInfo *)NULL;
   }
-  if (*color_image)
+  if (color_image && *color_image)
   {
     DestroyImage(*color_image);
     *color_image = (Image *)NULL;
   }
-  if (*alpha_image)
+  if (alpha_image && *alpha_image)
   {
     DestroyImage(*alpha_image);
     *alpha_image = (Image *)NULL;
-- 
2.40.0