From: Ken Sharp <ken.sharp@artifex.com>
Date: Wed, 21 Aug 2019 10:10:51 +0100
Subject: PDF interpreter - review .forceput security
Origin: http://git.ghostscript.com/?p=ghostpdl.git;a=commitdiff;h=cd1b1cacadac2479e291efe611979bdc1b3bdb19
Bug: https://bugs.ghostscript.com/show_bug.cgi?id=701450
Bug-Debian-Security: https://security-tracker.debian.org/tracker/CVE-2019-14817
Bug #701450 "Safer Mode Bypass by .forceput Exposure in .pdfexectoken"
By abusing the error handler it was possible to get the PDFDEBUG portion
of .pdfexectoken, which uses .forceput left readable.
Add an executeonly appropriately to make sure that clause isn't readable
no mstter what.
Review all the uses of .forceput searching for similar cases, add
executeonly as required to secure those. All cases in the PostScript
support files seem to be covered already.
---
Resource/Init/pdf_base.ps | 2 +-
Resource/Init/pdf_draw.ps | 14 +++++++-------
Resource/Init/pdf_font.ps | 29 ++++++++++++++++-------------
Resource/Init/pdf_main.ps | 6 +++---
Resource/Init/pdf_ops.ps | 11 ++++++-----
5 files changed, 33 insertions(+), 29 deletions(-)
diff --git a/Resource/Init/pdf_base.ps b/Resource/Init/pdf_base.ps
index 2e28cdd7181e..02503eef8bc4 100644
--- a/Resource/Init/pdf_base.ps
+++ b/Resource/Init/pdf_base.ps
@@ -157,7 +157,7 @@ currentdict /num-chars-dict .undef
{
dup ==only () = flush
} ifelse % PDFSTEP
- } if % PDFDEBUG
+ } executeonly if % PDFDEBUG
2 copy .knownget {
exch pop exch pop exch pop exec
} {
diff --git a/Resource/Init/pdf_draw.ps b/Resource/Init/pdf_draw.ps
index 11eb485f2eb7..fe3fc56c4161 100644
--- a/Resource/Init/pdf_draw.ps
+++ b/Resource/Init/pdf_draw.ps
@@ -501,8 +501,8 @@ end
( Output may be incorrect.\n) pdfformaterror
//pdfdict /.gs_warning_issued //true .forceput
PDFSTOPONERROR { /gs /undefined signalerror } if
- } if
- }
+ } executeonly if
+ } executeonly
ifelse
} bind executeonly def
@@ -1152,7 +1152,7 @@ currentdict end readonly def
.setglobal
pdfformaterror
} executeonly ifelse
- }
+ } executeonly
{
currentglobal //pdfdict gcheck .setglobal
//pdfdict /.Qqwarning_issued //true .forceput
@@ -1160,8 +1160,8 @@ currentdict end readonly def
pdfformaterror
} executeonly ifelse
end
- } ifelse
- } loop
+ } executeonly ifelse
+ } executeonly loop
{
(\n **** Error: File has unbalanced q/Q operators \(too many q's\)\n Output may be incorrect.\n)
//pdfdict /.Qqwarning_issued .knownget
@@ -1175,14 +1175,14 @@ currentdict end readonly def
.setglobal
pdfformaterror
} executeonly ifelse
- }
+ } executeonly
{
currentglobal //pdfdict gcheck .setglobal
//pdfdict /.Qqwarning_issued //true .forceput
.setglobal
pdfformaterror
} executeonly ifelse
- } if
+ } executeonly if
pop
% restore pdfemptycount
diff --git a/Resource/Init/pdf_font.ps b/Resource/Init/pdf_font.ps
index 8b8fef8..86b1870 100644
--- a/Resource/Init/pdf_font.ps
+++ b/Resource/Init/pdf_font.ps
@@ -677,7 +677,7 @@ currentdict end readonly def
currentglobal 2 index dup gcheck setglobal
/FontInfo 5 dict dup 5 1 roll .forceput
setglobal
- } if
+ } executeonly if
dup /GlyphNames2Unicode .knownget not {
//true % No existing G2U, make one
} {
@@ -701,9 +701,9 @@ currentdict end readonly def
} if
PDFDEBUG {
(.processToUnicode end) =
- } if
- } if
- } stopped
+ } executeonly if
+ } executeonly if
+ } executeonly stopped
{
.dstackdepth 1 countdictstack 1 sub
{pop end} for
@@ -1298,19 +1300,20 @@ currentdict /eexec_pdf_param_dict .undef
//pdfdict /.Qqwarning_issued //true .forceput
} executeonly if
Q
- } repeat
+ } executeonly repeat
Q
- } PDFfile fileposition 2 .execn % Keep pdfcount valid.
+ } executeonly PDFfile fileposition 2 .execn % Keep pdfcount valid.
PDFfile exch setfileposition
- } ifelse
- } {
+ } executeonly ifelse
+ } executeonly
+ {
% PDF Type 3 fonts don't use .notdef
% d1 implementation adjusts the width as needed
0 0 0 0 0 0
pdfopdict /d1 get exec
} ifelse
end end
- } bdef
+ } executeonly bdef
dup currentdict Encoding .processToUnicode
currentdict end .completefont exch pop
} bind executeonly odef
@@ -2124,9 +2127,9 @@ currentdict /CMap_read_dict undef
(Will continue, but content may be missing.) = flush
} ifelse
} if
- } if
+ } executeonly if
/findresource cvx /undefined signalerror
- } loop
+ } executeonly loop
} bind executeonly odef
/buildCIDType0 { % <CIDFontType0-font-resource> buildCIDType0 <font>
diff --git a/Resource/Init/pdf_main.ps b/Resource/Init/pdf_main.ps
index 00d7e3682fd8..7690bae0f920 100644
--- a/Resource/Init/pdf_main.ps
+++ b/Resource/Init/pdf_main.ps
@@ -2771,15 +2771,15 @@ currentdict /PDF2PS_matrix_key undef
.setglobal
pdfformaterror
} executeonly ifelse
- }
+ } executeonly
{
currentglobal //pdfdict gcheck .setglobal
//pdfdict /.Qqwarning_issued //true .forceput
.setglobal
pdfformaterror
} executeonly ifelse
- } if
- } if
+ } executeonly if
+ } executeonly if
pop
count PDFexecstackcount sub { pop } repeat
(after exec) VMDEBUG
diff --git a/Resource/Init/pdf_ops.ps b/Resource/Init/pdf_ops.ps
index a15c8c6770f7..d594035c066a 100644
--- a/Resource/Init/pdf_ops.ps
+++ b/Resource/Init/pdf_ops.ps
@@ -192,14 +192,14 @@ currentdict /gput_always_allow .undef
.setglobal
pdfformaterror
} executeonly ifelse
- }
+ } executeonly
{
currentglobal //pdfdict gcheck .setglobal
//pdfdict /.Qqwarning_issued //true .forceput
.setglobal
pdfformaterror
} executeonly ifelse
- } if
+ } executeonly if
} bind executeonly odef
% Save PDF gstate
@@ -446,11 +446,12 @@ currentdict /gput_always_allow .undef
dup type /booleantype eq {
.currentSMask type /dicttype eq {
.currentSMask /Processed 2 index .forceput
+ } executeonly
+ {
+ .setSMask
+ }ifelse
} executeonly
{
- .setSMask
- }ifelse
- }{
.setSMask
}ifelse
--
2.23.0.rc1
