Commit 4f7f6f6e47232e3df95174833c1c5bead20e8f9e
2015-10-11T07:55:25
[sfnt] Improve extraction of number of named instances. * src/sfnt/sfobjs.c (sfnt_init_face) [TT_CONFIG_OPTION_GX_VAR_SUPPORT]: Check number of instances against `fvar' table size.
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diff --git a/ChangeLog b/ChangeLog
index 9464b14..067bf74 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2015-10-11 Werner Lemberg <wl@gnu.org>
+
+ [sfnt] Improve extraction of number of named instances.
+
+ * src/sfnt/sfobjs.c (sfnt_init_face)
+ [TT_CONFIG_OPTION_GX_VAR_SUPPORT]: Check number of instances against
+ `fvar' table size.
+
2015-10-10 Alexei Podtelezhnikov <apodtele@gmail.com>
* src/base/ftoutln.c (FT_Outline_Get_Orientation): Fix overflow
diff --git a/src/sfnt/sfobjs.c b/src/sfnt/sfobjs.c
index 14d3ade..42c7222 100644
--- a/src/sfnt/sfobjs.c
+++ b/src/sfnt/sfobjs.c
@@ -883,9 +883,17 @@
#ifdef TT_CONFIG_OPTION_GX_VAR_SUPPORT
{
- FT_ULong fvar_len;
+ FT_ULong fvar_len;
+
+ FT_ULong version;
+ FT_ULong offset;
+
+ FT_UShort num_axes;
+ FT_UShort axis_size;
FT_UShort num_instances;
- FT_Int instance_index;
+ FT_UShort instance_size;
+
+ FT_Int instance_index;
instance_index = FT_ABS( face_instance_index ) >> 16;
@@ -893,8 +901,31 @@
/* test whether current face is a GX font with named instances */
if ( face->goto_table( face, TTAG_fvar, stream, &fvar_len ) ||
fvar_len < 20 ||
- FT_STREAM_SKIP( 12 ) ||
- FT_READ_USHORT( num_instances ) )
+ FT_READ_ULONG( version ) ||
+ FT_READ_USHORT( offset ) ||
+ FT_STREAM_SKIP( 2 ) ||
+ FT_READ_USHORT( num_axes ) ||
+ FT_READ_USHORT( axis_size ) ||
+ FT_READ_USHORT( num_instances ) ||
+ FT_READ_USHORT( instance_size ) )
+ {
+ version = 0;
+ num_axes = 0;
+ axis_size = 0;
+ num_instances = 0;
+ instance_size = 0;
+ }
+
+ /* check that the data is bound by the table length; */
+ /* based on similar code in function `TT_Get_MM_Var' */
+ if ( version != 0x00010000UL ||
+ axis_size != 20 ||
+ num_axes > 0x3FFE ||
+ instance_size != 4 + 4 * num_axes ||
+ num_instances > 0x7EFF ||
+ offset +
+ axis_size * num_axes +
+ instance_size * num_instances > fvar_len )
num_instances = 0;
/* we support at most 2^15 - 1 instances */