From: Ken Sharp Date: Wed, 21 Aug 2019 09:10:51 +0000 (+0100) Subject: PDF interpreter - review .forceput security X-Git-Url: http://git.ghostscript.com/?p=ghostpdl.git;a=commitdiff_plain;h=cd1b1cacadac2479e291efe611979bdc1b3bdb19 PDF interpreter - review .forceput security 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. --- diff --git a/Resource/Init/pdf_base.ps b/Resource/Init/pdf_base.ps index 2e28cdd..02503ee 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 11eb485..fe3fc56 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 da07da5..81b7af1 100644 --- a/Resource/Init/pdf_font.ps +++ b/Resource/Init/pdf_font.ps @@ -677,13 +677,13 @@ 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 - } { + } executeonly { dup wcheck { //false % Existing, writeable G2U, don't make new one - } { + } executeonly { pop //true % Existing read only G2U, make new one } ifelse } ifelse @@ -701,9 +701,9 @@ } if PDFDEBUG { (.processToUnicode end) = - } if - } if - } stopped + } executeonly if + } executeonly if + } executeonly stopped { .dstackdepth 1 countdictstack 1 sub {pop end} for @@ -1233,19 +1233,20 @@ //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 @@ -2045,9 +2046,9 @@ (Will continue, but content may be missing.) = flush } ifelse } if - } if + } executeonly if /findresource cvx /undefined signalerror - } loop + } executeonly loop } bind executeonly odef /buildCIDType0 { % buildCIDType0 diff --git a/Resource/Init/pdf_main.ps b/Resource/Init/pdf_main.ps index 00d7e36..7690bae 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 a15c8c6..d594035 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