Commit 4a89112b2a7c894c3bce22f7980e6513400f9525
2022-01-08T16:56:57
* src/sfnt/ttcolr.c (tt_face_get_color_glyph_clipbox): Add limit checks. Reported as https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=40716
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diff --git a/src/sfnt/ttcolr.c b/src/sfnt/ttcolr.c
index 8f5cc8b..326c0e9 100644
--- a/src/sfnt/ttcolr.c
+++ b/src/sfnt/ttcolr.c
@@ -824,7 +824,7 @@
{
Colr* colr;
- FT_Byte *p, *p1, *clip_base;
+ FT_Byte *p, *p1, *clip_base, *limit;
FT_Byte clip_list_format;
FT_ULong num_clip_boxes, i;
@@ -847,16 +847,28 @@
p = colr->clip_list;
+ limit = (FT_Byte*)colr->table + colr->table_size;
+
+ /* Check whether we can extract one `uint8` and one `uint32`. */
+ if ( p >= limit - ( 1 + 4 ) )
+ return 0;
+
clip_base = p;
clip_list_format = FT_NEXT_BYTE ( p );
/* Format byte used here to be able to upgrade ClipList for >16bit */
- /* glyph ids; for now we can expect it to be 0. */
+ /* glyph ids; for now we can expect it to be 0. */
if ( !( clip_list_format == 1 ) )
return 0;
num_clip_boxes = FT_NEXT_ULONG( p );
+ /* Check whether we can extract two `uint16` and one `Offset24`, */
+ /* `num_clip_boxes` times. */
+ if ( colr->table_size / ( 2 + 2 + 3 ) < num_clip_boxes ||
+ p >= limit - ( 2 + 2 + 3 ) * num_clip_boxes )
+ return 0;
+
for ( i = 0; i < num_clip_boxes; ++i )
{
gid_start = FT_NEXT_USHORT( p );
@@ -867,7 +879,8 @@
{
p1 = (FT_Byte*)( clip_base + clip_box_offset );
- if ( p1 >= ( (FT_Byte*)colr->table + colr->table_size ) )
+ /* Check whether we can extract one `uint8`. */
+ if ( p1 >= limit - 1 )
return 0;
format = FT_NEXT_BYTE( p1 );
@@ -875,6 +888,10 @@
if ( format > 1 )
return 0;
+ /* Check whether we can extract four `FWORD`. */
+ if ( p1 >= limit - ( 2 + 2 + 2 + 2 ) )
+ return 0;
+
/* `face->root.size->metrics.x_scale` and `y_scale` are factors */
/* that scale a font unit value in integers to a 26.6 fixed value */
/* according to the requested size, see for example */