The following patch was adapted for GNU Ghostscript
by Mark H Weaver <mhw@netris.org> based on:

http://git.ghostscript.com/?p=ghostpdl.git;a=commit;h=875a0095f37626a721c7ff57d606a0f95af03913

From 875a0095f37626a721c7ff57d606a0f95af03913 Mon Sep 17 00:00:00 2001
From: Ken Sharp <ken.sharp@artifex.com>
Date: Wed, 5 Oct 2016 10:10:58 +0100
Subject: [PATCH] DSC parser - validate parameters

Bug #697190 ".initialize_dsc_parser doesn't validate the parameter is a dict type before using it."

Regardless of any security implications, its simply wrong for a PostScript
operator not to validate its parameter(s).

No differences expected.
---
 psi/zdscpars.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

diff --git a/psi/zdscpars.c b/psi/zdscpars.c
index c05e154..9b4b605 100644
--- a/psi/zdscpars.c
+++ b/psi/zdscpars.c
@@ -150,11 +150,16 @@ zinitialize_dsc_parser(i_ctx_t *i_ctx_p)
     ref local_ref;
     int code;
     os_ptr const op = osp;
-    dict * const pdict = op->value.pdict;
-    gs_memory_t * const mem = (gs_memory_t *)dict_memory(pdict);
-    dsc_data_t * const data =
-        gs_alloc_struct(mem, dsc_data_t, &st_dsc_data_t, "DSC parser init");
+    dict *pdict;
+    gs_memory_t *mem;
+    dsc_data_t *data;
 
+    check_read_type(*op, t_dictionary);
+
+    pdict = op->value.pdict;
+    mem = (gs_memory_t *)dict_memory(pdict);
+
+    data = gs_alloc_struct(mem, dsc_data_t, &st_dsc_data_t, "DSC parser init");
     if (!data)
         return_error(e_VMerror);
     data->document_level = 0;
-- 
2.9.1

