ref: da34673e54e2fd03f25b69a3a3c5bf2c6862c866
parent: c220d8b498a66e241872ea4b39a8902177e5fac3
author: Werner Lemberg <[email protected]>
date: Sat Oct 10 06:21:27 EDT 2015
[truetype] More sanity tests for GX handling. These tests should mainly help avoid unnecessarily large memory allocations in case of malformed fonts. * src/truetype/ttgxvar.c (ft_var_readpackedpoints, ft_var_readpackeddeltas): Check number of points against stream size. (ft_var_load_avar): Check `pairCount' against table length. (ft_var_load_gvar): Check `globalCoordCount' and `glyphCount' against table length. (tt_face_vary_cvt): Check `tupleCount' and `offsetToData'. Fix trace. (TT_Vary_Apply_Glyph_Deltas): Fix trace. Free `sharedpoints' to avoid memory leak.
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,5 +1,23 @@
2015-10-10 Werner Lemberg <[email protected]>
+ [truetype] More sanity tests for GX handling.
+
+ These tests should mainly help avoid unnecessarily large memory
+ allocations in case of malformed fonts.
+
+ * src/truetype/ttgxvar.c (ft_var_readpackedpoints,
+ ft_var_readpackeddeltas): Check number of points against stream
+ size.
+ (ft_var_load_avar): Check `pairCount' against table length.
+ (ft_var_load_gvar): Check `globalCoordCount' and `glyphCount'
+ against table length.
+ (tt_face_vary_cvt): Check `tupleCount' and `offsetToData'.
+ Fix trace.
+ (TT_Vary_Apply_Glyph_Deltas): Fix trace.
+ Free `sharedpoints' to avoid memory leak.
+
+2015-10-10 Werner Lemberg <[email protected]>
+
[truetype] Better protection against malformed GX data (#46166).
* src/truetype/ttgxvar.c (TT_Vary_Apply_Glyph_Deltas): Correctly
--- a/src/truetype/ttgxvar.c
+++ b/src/truetype/ttgxvar.c
@@ -149,6 +149,12 @@
n |= FT_GET_BYTE();
}
+ if ( n > stream->size - stream->pos )
+ {+ FT_TRACE1(( "ft_var_readpackedpoints: number of points too large\n" ));
+ return NULL;
+ }
+
if ( FT_NEW_ARRAY( points, n ) )
return NULL;
@@ -233,6 +239,12 @@
FT_UNUSED( error );
+ if ( delta_cnt > stream->size - stream->pos )
+ {+ FT_TRACE1(( "ft_var_readpackeddeltas: number of points too large\n" ));
+ return NULL;
+ }
+
if ( FT_NEW_ARRAY( deltas, delta_cnt ) )
return NULL;
@@ -341,7 +353,8 @@
FT_TRACE5(( " axis %d:\n", i ));
segment->pairCount = FT_GET_USHORT();
- if ( FT_NEW_ARRAY( segment->correspondence, segment->pairCount ) )
+ if ( (FT_ULong)segment->pairCount * 4 > table_len ||
+ FT_NEW_ARRAY( segment->correspondence, segment->pairCount ) )
{/* Failure. Free everything we have done so far. We must do */
/* it right now since loading the `avar' table is optional. */
@@ -447,10 +460,6 @@
if ( FT_STREAM_READ_FIELDS( gvar_fields, &gvar_head ) )
goto Exit;
- blend->tuplecount = gvar_head.globalCoordCount;
- blend->gv_glyphcnt = gvar_head.glyphCount;
- offsetToData = gvar_start + gvar_head.offsetToData;
-
if ( gvar_head.version != 0x00010000L )
{FT_TRACE1(( "bad table version\n" ));
@@ -458,8 +467,6 @@
goto Exit;
}
- FT_TRACE2(( "loaded\n" ));
-
if ( gvar_head.axisCount != (FT_UShort)blend->mmvar->num_axis )
{FT_TRACE1(( "ft_var_load_gvar: number of axes in `gvar' and `cvar'\n"
@@ -468,6 +475,27 @@
goto Exit;
}
+ /* rough sanity check, ignoring offsets */
+ if ( (FT_ULong)gvar_head.globalCoordCount * gvar_head.axisCount >
+ table_len / 2 )
+ {+ FT_TRACE1(( "ft_var_load_gvar:"
+ " invalid number of global coordinates\n" ));
+ error = FT_THROW( Invalid_Table );
+ goto Exit;
+ }
+
+ /* rough sanity check: offsets can be either 2 or 4 bytes, */
+ /* and a single variation needs at least 4 bytes per glyph */
+ if ( (FT_ULong)gvar_head.glyphCount *
+ ( ( gvar_head.flags & 1 ) ? 8 : 6 ) > table_len )
+
+ FT_TRACE2(( "loaded\n" ));
+
+ blend->tuplecount = gvar_head.globalCoordCount;
+ blend->gv_glyphcnt = gvar_head.glyphCount;
+ offsetToData = gvar_start + gvar_head.offsetToData;
+
FT_TRACE5(( "gvar: there are %d shared coordinates:\n",
blend->tuplecount ));
@@ -1353,14 +1381,26 @@
goto FExit;
tupleCount = FT_GET_USHORT();
- offsetToData = table_start + FT_GET_USHORT();
+ offsetToData = FT_GET_USHORT();
- /* The documentation implies there are flags packed into the */
- /* tuplecount, but John Jenkins says that shared points don't apply */
- /* to `cvar', and no other flags are defined. */
+ /* rough sanity test */
+ if ( offsetToData + tupleCount * 4 > table_len )
+ {+ FT_TRACE2(( "tt_face_vary_cvt:"
+ " invalid CVT variation array header\n" ));
- FT_TRACE5(( "cvar: there are %d tuples:\n", tupleCount ));
+ error = FT_THROW( Invalid_Table );
+ goto FExit;
+ }
+ offsetToData += table_start;
+
+ /* The documentation implies there are flags packed into */
+ /* `tupleCount', but John Jenkins says that shared points don't apply */
+ /* to `cvar', and no other flags are defined. */
+
+ FT_TRACE5(( "cvar: there are %d tuples:\n", tupleCount & 0xFFF ));
+
for ( i = 0; i < ( tupleCount & 0xFFF ); i++ )
{FT_UInt tupleDataSize;
@@ -1833,7 +1873,8 @@
FT_Stream_SeekSet( stream, here );
}
- FT_TRACE5(( "gvar: there are %d tuples:\n", tupleCount ));
+ FT_TRACE5(( "gvar: there are %d tuples:\n",
+ tupleCount & GX_TC_TUPLE_COUNT_MASK ));
for ( i = 0; i < ( tupleCount & GX_TC_TUPLE_COUNT_MASK ); i++ )
{@@ -2013,6 +2054,8 @@
if ( localpoints != ALL_POINTS )
FT_FREE( localpoints );
+ if ( sharedpoints != ALL_POINTS )
+ FT_FREE( sharedpoints );
FT_FREE( deltas_x );
FT_FREE( deltas_y );