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From 239ef121fed25aa478b740bf52dce4db1a00ba59 Mon Sep 17 00:00:00 2001
From: Sona Sarmadi <sona.sarmadi@enea.com>
Date: Mon, 28 Aug 2017 14:12:29 +0200
Subject: [PATCH] freetype: fix for CVE-2017-8105
[psaux] Better protect `flex' handling.
Reported as
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=935
* src/psaux/t1decode.c (t1_decoder_parse_charstrings)
<callothersubr>: Since there is not a single flex operator but a
series of subroutine calls, malformed fonts can call arbitrary other
operators after the start of a flex, possibly adding points. For
this reason we have to check the available number of points before
inserting a point.
CVE: CVE-2017-8105
Upstream-Status: Backport [http://git.savannah.gnu.org/cgit/freetype/freetype2.git/commit/?id=f958c48ee431bef8d4d466b40c9cb2d4dbcb7791]
Signed-off-by: Sona Sarmadi <sona.sarmadi@enea.com>
---
ChangeLog | 15 +++++++++++++++
src/psaux/t1decode.c | 9 +++++++++
2 files changed, 24 insertions(+)
diff --git a/ChangeLog b/ChangeLog
index 23f5748..2f89909 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,18 @@
+2017-03-23 Werner Lemberg <wl@gnu.org>
+
+ [psaux] Better protect `flex' handling.
+
+ Reported as
+
+ https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=935
+
+ * src/psaux/t1decode.c (t1_decoder_parse_charstrings)
+ <callothersubr>: Since there is not a single flex operator but a
+ series of subroutine calls, malformed fonts can call arbitrary other
+ operators after the start of a flex, possibly adding points. For
+ this reason we have to check the available number of points before
+ inserting a point.
+
2016-09-08 Werner Lemberg <wl@gnu.org>
* Version 2.7.1 released.
diff --git a/src/psaux/t1decode.c b/src/psaux/t1decode.c
index 1cd9d73..bc5e3d2 100644
--- a/src/psaux/t1decode.c
+++ b/src/psaux/t1decode.c
@@ -780,10 +780,19 @@
/* point without adding any point to the outline */
idx = decoder->num_flex_vectors++;
if ( idx > 0 && idx < 7 )
+ {
+ /* in malformed fonts it is possible to have other */
+ /* opcodes in the middle of a flex (which don't */
+ /* increase `num_flex_vectors'); we thus have to */
+ /* check whether we can add a point */
+ if ( FT_SET_ERROR( t1_builder_check_points( builder, 1 ) ) )
+ goto Syntax_Error;
+
t1_builder_add_point( builder,
x,
y,
(FT_Byte)( idx == 3 || idx == 6 ) );
+ }
}
break;
--
1.9.1
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