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Code Issues 4 Releases Wiki Activity

[sfnt] Guard access in 'COLR' table when requesting child table pointer. 

* src/sfnt/ttcolr.c (tt_face_get_colorline_stops, read_paint): Tighten
pointer bounds checks.
(get_child_table_pointer): Check whether incoming pointer `p` lies within
the 'COLR' table.

Reported as

  https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=51816
This commit is contained in:
Dominik Röttsches 2022-09-27 17:50:55 +03:00 committed by Werner Lemberg
parent bd41700773
commit df2601395f
1 changed files with 13 additions and 5 deletions
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18
src/sfnt/ttcolr.c
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@ -554,6 +554,10 @@
if ( !child_table_pointer )
return 0;
if ( *p < colr->paints_start_v1 ||
*p > (FT_Byte*)colr->table + colr->table_size - 1 - 3 )
return 0;
paint_offset = FT_NEXT_UOFF3( *p );
if ( !paint_offset )
return 0;
@ -650,8 +654,10 @@
if ( !p || !colr || !colr->table )
return 0;
if ( p < colr->paints_start_v1 ||
p >= ( (FT_Byte*)colr->table + colr->table_size ) )
/* The last byte of the 'COLR' table is at 'size-1'; subtract 1 of */
/* that to account for the expected format byte we are going to read. */
if ( p < colr->paints_start_v1 ||
p > (FT_Byte*)colr->table + colr->table_size - 2 )
return 0;
apaint->format = (FT_PaintFormat)FT_NEXT_BYTE( p );
@ -1577,10 +1583,12 @@
if ( iterator->current_color_stop >= iterator->num_color_stops )
return 0;
/* Subtract 3 times 2 because we need to succeed in reading */
/* three 2-byte short values. */
if ( iterator->p +
( ( iterator->num_color_stops - iterator->current_color_stop ) *
COLOR_STOP_SIZE ) >
( (FT_Byte *)colr->table + colr->table_size ) )
( iterator->num_color_stops - iterator->current_color_stop ) *
COLOR_STOP_SIZE >
(FT_Byte*)colr->table + colr->table_size - 1 - 2 - 2 - 2 )
return 0;
/* Iterator points at first `ColorStop` of `ColorLine`. */