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Ghostscript 9.24 was released with an incomplete fix for CVE-2018-16509:
https://nvd.nist.gov/vuln/detail/CVE-2018-16509
https://bugs.chromium.org/p/project-zero/issues/detail?id=1640#c19
https://bugs.ghostscript.com/show_bug.cgi?id=699718
The reproducers no longer work after applying these commits:
https://git.ghostscript.com/?p=ghostpdl.git;a=commitdiff;h=5812b1b78fc4d36fdc293b7859de69241140d590
https://git.ghostscript.com/?p=ghostpdl.git;a=commitdiff;h=e914f1da46e33decc534486598dc3eadf69e6efb
https://git.ghostscript.com/?p=ghostpdl.git;a=commitdiff;h=3e5d316b72e3965b7968bb1d96baa137cd063ac6
https://git.ghostscript.com/?p=ghostpdl.git;a=commitdiff;h=643b24dbd002fb9c131313253c307cf3951b3d47
This patch is a "squashed" version of those.
diff --git a/Resource/Init/gs_setpd.ps b/Resource/Init/gs_setpd.ps
index bba3c8c0e..8fa7c51df 100644
--- a/Resource/Init/gs_setpd.ps
+++ b/Resource/Init/gs_setpd.ps
@@ -95,27 +95,41 @@ level2dict begin
{ % Since setpagedevice doesn't create new device objects,
% we must (carefully) reinstall the old parameters in
% the same device.
- .currentpagedevice pop //null currentdevice //null .trysetparams
+ .currentpagedevice pop //null currentdevice //null
+ { .trysetparams } .internalstopped
+ {
+ //null
+ } if
dup type /booleantype eq
{ pop pop }
- { % This should never happen!
+ {
SETPDDEBUG { (Error in .trysetparams!) = pstack flush } if
- cleartomark pop pop pop
+ {cleartomark pop pop pop} .internalstopped pop
+ % if resetting the entire device state failed, at least put back the
+ % security related key
+ currentdevice //null //false mark /.LockSafetyParams
+ currentpagedevice /.LockSafetyParams .knownget not
+ {systemdict /SAFER .knownget not {//false} } if
+ .putdeviceparamsonly
/.installpagedevice cvx /rangecheck signalerror
}
ifelse pop pop
% A careful reading of the Red Book reveals that an erasepage
% should occur, but *not* an initgraphics.
erasepage .beginpage
- } bind def
+ } bind executeonly def
/.uninstallpagedevice
- { 2 .endpage { .currentnumcopies //false .outputpage } if
+ {
+ {2 .endpage { .currentnumcopies //false .outputpage } if} .internalstopped pop
nulldevice
} bind def
(%grestorepagedevice) cvn
- { .uninstallpagedevice grestore .installpagedevice
+ {
+ .uninstallpagedevice
+ grestore
+ .installpagedevice
} bind def
(%grestoreallpagedevice) cvn
diff --git a/psi/zdevice2.c b/psi/zdevice2.c
index 0c7080d57..159a0c0d9 100644
--- a/psi/zdevice2.c
+++ b/psi/zdevice2.c
@@ -251,8 +251,8 @@ z2currentgstate(i_ctx_t *i_ctx_p)
/* ------ Wrappers for operators that reset the graphics state. ------ */
/* Check whether we need to call out to restore the page device. */
-static bool
-restore_page_device(const gs_gstate * pgs_old, const gs_gstate * pgs_new)
+static int
+restore_page_device(i_ctx_t *i_ctx_p, const gs_gstate * pgs_old, const gs_gstate * pgs_new)
{
gx_device *dev_old = gs_currentdevice(pgs_old);
gx_device *dev_new;
@@ -260,9 +260,10 @@ restore_page_device(const gs_gstate * pgs_old, const gs_gstate * pgs_new)
gx_device *dev_t2;
bool samepagedevice = obj_eq(dev_old->memory, &gs_int_gstate(pgs_old)->pagedevice,
&gs_int_gstate(pgs_new)->pagedevice);
+ bool LockSafetyParams = dev_old->LockSafetyParams;
if ((dev_t1 = (*dev_proc(dev_old, get_page_device)) (dev_old)) == 0)
- return false;
+ return 0;
/* If we are going to putdeviceparams in a callout, we need to */
/* unlock temporarily. The device will be re-locked as needed */
/* by putdeviceparams from the pgs_old->pagedevice dict state. */
@@ -271,23 +272,51 @@ restore_page_device(const gs_gstate * pgs_old, const gs_gstate * pgs_new)
dev_new = gs_currentdevice(pgs_new);
if (dev_old != dev_new) {
if ((dev_t2 = (*dev_proc(dev_new, get_page_device)) (dev_new)) == 0)
- return false;
- if (dev_t1 != dev_t2)
- return true;
+ samepagedevice = true;
+ else if (dev_t1 != dev_t2)
+ samepagedevice = false;
+ }
+
+ if (LockSafetyParams && !samepagedevice) {
+ const int required_ops = 512;
+ const int required_es = 32;
+
+ /* The %grestorepagedevice must complete: the biggest danger
+ is operand stack overflow. As we use get/putdeviceparams
+ that means pushing all the device params onto the stack,
+ pdfwrite having by far the largest number of parameters
+ at (currently) 212 key/value pairs - thus needing (currently)
+ 424 entries on the op stack. Allowing for working stack
+ space, and safety margin.....
+ */
+ if (required_ops + ref_stack_count(&o_stack) >= ref_stack_max_count(&o_stack)) {
+ gs_currentdevice(pgs_old)->LockSafetyParams = LockSafetyParams;
+ return_error(gs_error_stackoverflow);
+ }
+ /* We also want enough exec stack space - 32 is an overestimate of
+ what we need to complete the Postscript call out.
+ */
+ if (required_es + ref_stack_count(&e_stack) >= ref_stack_max_count(&e_stack)) {
+ gs_currentdevice(pgs_old)->LockSafetyParams = LockSafetyParams;
+ return_error(gs_error_execstackoverflow);
+ }
}
/*
* The current implementation of setpagedevice just sets new
* parameters in the same device object, so we have to check
* whether the page device dictionaries are the same.
*/
- return !samepagedevice;
+ return samepagedevice ? 0 : 1;
}
/* - grestore - */
static int
z2grestore(i_ctx_t *i_ctx_p)
{
- if (!restore_page_device(igs, gs_gstate_saved(igs)))
+ int code = restore_page_device(i_ctx_p, igs, gs_gstate_saved(igs));
+ if (code < 0) return code;
+
+ if (code == 0)
return gs_grestore(igs);
return push_callout(i_ctx_p, "%grestorepagedevice");
}
@@ -297,7 +326,9 @@ static int
z2grestoreall(i_ctx_t *i_ctx_p)
{
for (;;) {
- if (!restore_page_device(igs, gs_gstate_saved(igs))) {
+ int code = restore_page_device(i_ctx_p, igs, gs_gstate_saved(igs));
+ if (code < 0) return code;
+ if (code == 0) {
bool done = !gs_gstate_saved(gs_gstate_saved(igs));
gs_grestore(igs);
@@ -328,11 +359,15 @@ z2restore(i_ctx_t *i_ctx_p)
if (code < 0) return code;
while (gs_gstate_saved(gs_gstate_saved(igs))) {
- if (restore_page_device(igs, gs_gstate_saved(igs)))
+ code = restore_page_device(i_ctx_p, igs, gs_gstate_saved(igs));
+ if (code < 0) return code;
+ if (code > 0)
return push_callout(i_ctx_p, "%restore1pagedevice");
gs_grestore(igs);
}
- if (restore_page_device(igs, gs_gstate_saved(igs)))
+ code = restore_page_device(i_ctx_p, igs, gs_gstate_saved(igs));
+ if (code < 0) return code;
+ if (code > 0)
return push_callout(i_ctx_p, "%restorepagedevice");
code = dorestore(i_ctx_p, asave);
@@ -355,9 +390,12 @@ static int
z2setgstate(i_ctx_t *i_ctx_p)
{
os_ptr op = osp;
+ int code;
check_stype(*op, st_igstate_obj);
- if (!restore_page_device(igs, igstate_ptr(op)))
+ code = restore_page_device(i_ctx_p, igs, igstate_ptr(op));
+ if (code < 0) return code;
+ if (code == 0)
return zsetgstate(i_ctx_p);
return push_callout(i_ctx_p, "%setgstatepagedevice");
}
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