diff -up ImageMagick-6.7.8-9/magick/constitute.c.null-pointer-access ImageMagick-6.7.8-9/magick/constitute.c

--- ImageMagick-6.7.8-9/magick/constitute.c.null-pointer-access	2012-07-29 22:26:50.000000000 +0200

+++ ImageMagick-6.7.8-9/magick/constitute.c	2016-06-02 17:32:26.990718329 +0200

@@ -1324,7 +1324,7 @@ MagickExport MagickBooleanType WriteImag

     status;

   register Image

-    *p;

+    *p, *next_p;

   assert(image_info != (const ImageInfo *) NULL);

   assert(image_info->signature == MagickSignature);

@@ -1349,8 +1349,11 @@ MagickExport MagickBooleanType WriteImag

     sans_exception);

   sans_exception=DestroyExceptionInfo(sans_exception);

   p=images;

-  for ( ; GetNextImageInList(p) != (Image *) NULL; p=GetNextImageInList(p))

-    if (p->scene >= GetNextImageInList(p)->scene)

+  for ( ; GetNextImageInList(p) != (Image *) NULL; p=GetNextImageInList(p)) {

+    next_p = GetNextImageInList(p);

+    if (next_p == (Image *) NULL)

+      break;

+    if (p->scene >= next_p->scene)

       {

         register ssize_t

           i;

@@ -1363,6 +1366,7 @@ MagickExport MagickBooleanType WriteImag

           p->scene=(size_t) i++;

         break;

       }

+  }

   /*

     Write images.

   */