ghostscript: add patch for CVE-2019-14869

again, context-adjusted patch cribbed from debian's 9.26a~dfsg-0+deb9u6

pkgs/misc/ghostscript/9.26-CVE-2019-14869.patch

@@ -0,0 +1,58 @@
+From: Chris Liddell <chris.liddell@artifex.com>
+Date: Tue, 5 Nov 2019 09:45:27 +0000
+Subject: Bug 701841: remove .forceput from /.charkeys
+Origin: https://git.ghostscript.com/?p=ghostpdl.git;a=commit;h=485904772c5f0aa1140032746e5a0abfc40f4cef
+Bug: https://bugs.ghostscript.com/show_bug.cgi?id=701841
+Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2019-14869
+
+When loading Type 1 or Truetype fonts from disk, we attempt to extend the glyph
+name table to include all identifiable glyph names from the Adobe Glyph List.
+
+In the case of Type 1 fonts, the font itself (almost always) marks the
+CharStrings dictionary as read-only, hence we have to use .forceput for that
+case.
+
+But for Truetype fonts, the CharStrings dictionary is created internally and is
+not read-only until *after* we have fully populated it (including the extended
+glyph names from the AGL), hence there is no need for .forceput, and no need to
+carry the security risk of using it.
+
+Replace with regular put.
+[Salvatore Bonaccorso: Backport to 9.26a: Drop last hunck removing
+'executeonly' (hiding .forceput) as this was never added back in 9.26a. Thanks
+to Marc Deslauriers for pointing this out]
+---
+ Resource/Init/gs_ttf.ps | 8 ++++----
+ 1 file changed, 4 insertions(+), 4 deletions(-)
+
+diff --git a/Resource/Init/gs_ttf.ps b/Resource/Init/gs_ttf.ps
+index 74043d16b0cf..6be8fe9955cd 100644
+--- a/Resource/Init/gs_ttf.ps
++++ b/Resource/Init/gs_ttf.ps
+@@ -1304,7 +1304,7 @@ currentdict /.pickcmap_with_no_xlatmap .undef
+           TTFDEBUG { (\n1 setting alias: ) print dup ==only
+                 ( to be the same as  ) print 2 index //== exec } if
+
+-          7 index 2 index 3 -1 roll exch .forceput
++          7 index 2 index 3 -1 roll exch put
+         } forall
+         pop pop pop
+       }
+@@ -1322,7 +1322,7 @@ currentdict /.pickcmap_with_no_xlatmap .undef
+           exch pop
+           TTFDEBUG { (\n2 setting alias: ) print 1 index ==only
+                      ( to use glyph index: ) print dup //== exec } if
+-          5 index 3 1 roll .forceput
++          5 index 3 1 roll put
+           //false
+         }
+         {
+@@ -1339,7 +1339,7 @@ currentdict /.pickcmap_with_no_xlatmap .undef
+         {                            %  CharStrings(dict) isunicode(boolean) cmap(dict) RAGL(dict) gname(name) codep(integer) gindex(integer)
+           TTFDEBUG { (\3 nsetting alias: ) print 1 index ==only
+                 ( to be index: ) print dup //== exec } if
+-          exch pop 5 index 3 1 roll .forceput
++          exch pop 5 index 3 1 roll put
+         }
+         {
+           pop pop

pkgs/misc/ghostscript/default.nix

@@ -82,6 +82,7 @@ stdenv.mkDerivation rec {
         excludes = ["Resource/Init/pdf_font.ps" "Resource/Init/pdf_draw.ps"];
         sha256 = "04sy05svm3d2hyyzq41x5aqg3cgg2shaq08ivdqsys95nlihccpn";
     })
+    ./9.26-CVE-2019-14869.patch
   ];
 
   outputs = [ "out" "man" "doc" ];