From d739565534e955c4336731e4ea4eebc895c09c5c Mon Sep 17 00:00:00 2001
From: Chris Liddell <chris.liddell@artifex.com>
Date: Tue, 18 Dec 2018 10:42:10 +0000
Subject: [PATCH 4/7] Harden some uses of .force* operators

by adding a few immediate evalutions

CVE: CVE-2019-6116
Upstream-Status: Backport [git://git.ghostscript.com/ghostpdl.git]

Signed-off-by: Ovidiu Panait <ovidiu.panait@windriver.com>
---
 Resource/Init/gs_dps1.ps  |  4 ++--
 Resource/Init/gs_fonts.ps | 20 ++++++++++----------
 Resource/Init/gs_init.ps  |  6 +++---
 3 files changed, 15 insertions(+), 15 deletions(-)

diff --git a/Resource/Init/gs_dps1.ps b/Resource/Init/gs_dps1.ps
index 4fae283..b75ea14 100644
--- a/Resource/Init/gs_dps1.ps
+++ b/Resource/Init/gs_dps1.ps
@@ -74,7 +74,7 @@ level2dict begin
  } odef
 % undefinefont has to take local/global VM into account.
 /undefinefont		% <fontname> undefinefont -
- { .FontDirectory 1 .argindex .forceundef	% FontDirectory is readonly
+ { //.FontDirectory 1 .argindex .forceundef	% FontDirectory is readonly
    .currentglobal
     {		% Current mode is global; delete from local directory too.
       //systemdict /LocalFontDirectory .knownget
@@ -85,7 +85,7 @@ level2dict begin
                 % definition, copy it into the local directory.
       //systemdict /SharedFontDirectory .knownget
        { 1 index .knownget
-          { .FontDirectory 2 index 3 -1 roll { put } systemdict /superexec known {//superexec}{1183615869 internaldict /superexec get exec} ifelse } % readonly
+          { //.FontDirectory 2 index 3 -1 roll { put } systemdict /superexec known {//superexec}{1183615869 internaldict /superexec get exec} ifelse } % readonly
          if
        }
       if
diff --git a/Resource/Init/gs_fonts.ps b/Resource/Init/gs_fonts.ps
index 290da0c..c13a2fc 100644
--- a/Resource/Init/gs_fonts.ps
+++ b/Resource/Init/gs_fonts.ps
@@ -516,7 +516,7 @@ buildfontdict 3 /.buildfont3 cvx put
       if
     }
    if
-   dup .FontDirectory 4 -2 roll { .growput } systemdict /superexec known {//superexec}{1183615869 internaldict /superexec get exec} ifelse	% readonly
+   dup //.FontDirectory 4 -2 roll { .growput } systemdict /superexec known {//superexec}{1183615869 internaldict /superexec get exec} ifelse	% readonly
                 % If the font originated as a resource, register it.
    currentfile .currentresourcefile eq { dup .registerfont } if
    readonly
@@ -943,7 +943,7 @@ $error /SubstituteFont { } put
 % Try to find a font using only the present contents of Fontmap.
 /.tryfindfont {         % <fontname> .tryfindfont <font> true
                         % <fontname> .tryfindfont false
-  .FontDirectory 1 index .fontknownget
+  //.FontDirectory 1 index .fontknownget
     {                   % Already loaded
       exch pop //true
     }
@@ -975,7 +975,7 @@ $error /SubstituteFont { } put
                {                % Font with a procedural definition
                  exec           % The procedure will load the font.
                                 % Check to make sure this really happened.
-                 .FontDirectory 1 index .knownget
+                 //.FontDirectory 1 index .knownget
                   { exch pop //true exit }
                  if
                }
@@ -1081,11 +1081,11 @@ $error /SubstituteFont { } put
                 % because it's different depending on language level.
            .currentglobal exch /.setglobal .systemvar exec
                 % Remove the fake definition, if any.
-           .FontDirectory 3 index .forceundef		% readonly
-           1 index (r) file .loadfont .FontDirectory exch
+           //.FontDirectory 3 index .forceundef		% readonly
+           1 index (r) file .loadfont //.FontDirectory exch
            /.setglobal .systemvar exec
          } executeonly
-         { .loadfont .FontDirectory
+         { .loadfont //.FontDirectory
          }
         ifelse
                 % Stack: fontname fontfilename fontdirectory
@@ -1119,8 +1119,8 @@ $error /SubstituteFont { } put
                       % Stack: origfontname fontdirectory filefontname fontdict
               3 -1 roll pop
                       % Stack: origfontname filefontname fontdict
-              dup /FontName get dup FontDirectory exch .forceundef
-              GlobalFontDirectory exch .forceundef
+              dup /FontName get dup //.FontDirectory exch .forceundef
+              /GlobalFontDirectory .systemvar exch .forceundef
               dup length dict .copydict dup 3 index /FontName exch put
               2 index exch definefont
               exch
@@ -1176,10 +1176,10 @@ currentdict /.putgstringcopy .undef
       {
         {
           pop dup type /stringtype eq { cvn } if
-          .FontDirectory 1 index known not {
+          //.FontDirectory 1 index known not {
             2 dict dup /FontName 3 index put
             dup /FontType 1 put
-            .FontDirectory 3 1 roll { put } systemdict /superexec known {//superexec}{1183615869 internaldict /superexec get exec} ifelse   % readonly
+            //.FontDirectory 3 1 roll { put } systemdict /superexec known {//superexec}{1183615869 internaldict /superexec get exec} ifelse   % readonly
           } {
             pop
           } ifelse
diff --git a/Resource/Init/gs_init.ps b/Resource/Init/gs_init.ps
index 56c0bd2..d9a0829 100644
--- a/Resource/Init/gs_init.ps
+++ b/Resource/Init/gs_init.ps
@@ -1168,8 +1168,8 @@ errordict /unknownerror .undef
     }ifelse
   }forall
   noaccess pop
-  systemdict /.setsafeerrors .forceundef
-  systemdict /.SAFERERRORLIST .forceundef
+  //systemdict /.setsafeerrors .forceundef
+  //systemdict /.SAFERERRORLIST .forceundef
 } bind executeonly odef
 
 SAFERERRORS {.setsafererrors} if
@@ -2114,7 +2114,7 @@ currentdict /tempfilepaths undef
 
 /.locksafe {
   .locksafe_userparams
-  systemdict /getenv {pop //false} .forceput
+  //systemdict /getenv {pop //false} .forceput
   % setpagedevice has the side effect of clearing the page, but
   % we will just document that. Using setpagedevice keeps the device
   % properties and pagedevice .LockSafetyParams in agreement even
-- 
2.18.1