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[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.
This commit is contained in:
Werner Lemberg 2015-10-10 10:21:27 +02:00
parent c220d8b498
commit da34673e54
2 changed files with 74 additions and 13 deletions
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18
ChangeLog
View File

@ -1,3 +1,21 @@
2015-10-10 Werner Lemberg <wl@gnu.org>
[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 <wl@gnu.org>
[truetype] Better protection against malformed GX data (#46166).

69
src/truetype/ttgxvar.c
View File

@ -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 ));
@ -1353,13 +1381,25 @@
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++ )
{
@ -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 );