From f958c48ee431bef8d4d466b40c9cb2d4dbcb7791 Mon Sep 17 00:00:00 2001 From: Werner Lemberg Date: Fri, 24 Mar 2017 09:15:10 +0100 Subject: [PATCH] [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) : 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. --- ChangeLog | 15 +++++++++++++++ src/psaux/t1decode.c | 9 +++++++++ 2 files changed, 24 insertions(+) diff --git a/ChangeLog b/ChangeLog index a98267a63..01e9a7be1 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,18 @@ +2017-03-23 Werner Lemberg + + [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) + : 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. + 2017-03-23 Werner Lemberg [sfnt] Fix check for default named instance. diff --git a/src/psaux/t1decode.c b/src/psaux/t1decode.c index af7b465ed..7dd45135d 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;