The `SVG_DOCUMENT_LIST_MINIMUM_SIZE` macro is non trivial and not
protected by parentheses. As a result, the expression
`table_size - SVG_DOCUMENT_LIST_MINIMUM_SIZE` expands to
`table_size - 2U + SVG_DOCUMENT_RECORD_SIZE` instead of the expected
`table_size - (2U + SVG_DOCUMENT_RECORD_SIZE)`. This causes an incorrect
bounds check which may lead to reading past the end of the `SVG ` table.
* src/sfnt/ttsvg.c (tt_face_load_svg): wrap macro definitions in
parentheses.
Bug: https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=45179
* src/sfnt/ttsvg.c (SVG_TABLE_HEADER_SIZE, SVG_DOCUMENT_RECORD_SIZE,
SVG_DOCUMENT_LIST_MINIMUM_SIZE, SVG_MINIMUM_SIZE): New macros.
(tt_face_load_svg): Check offsets.
Check table and record sizes.
Reported as
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=43918
* include/freetype/config/ftheader.h (FT_OTSVG_H): New macro.
* include/freetype/freetype.h (FT_FACE_FLAG_SVG, FT_HAS_SVG): New macros.
(FT_LOAD_SVG_ONLY): New internal macro.
* include/freetype/ftimage.h (FT_Glyph_Format): New enumeration value
`FT_GLYPH_FORMAT_SVG`.
* include/freetype/internal/ftobjs.h (FT_GLYPH_OWN_GZIP_SVG): New macro.
* include/freetype/internal/fttrace.h: Add `ttsvg` for `ttsvg.c`.
* include/freetype/internal/sfnt.h(load_svg, free_svg, load_svg_doc): New
functions.
* include/freetype/internal/tttypes.h (TT_FaceRec): Add `svg` for
the SVG table.
* include/freetype/otsvg.h (FT_SVG_DocumentRec): New structure to hold the
SVG document and other necessary information of an OT-SVG glyph in a glyph
slot.
* include/freetype/tttags.h (TTAG_SVG): New macro.
* src/base/ftobjs.c: Include `otsvg.h`.
(ft_glyphslot_init): Allocate `FT_SVG_DocumentRec` in `slot->other`
if the SVG table exists.
(ft_glyphslot_clear): Free it upon clean-up if it is a GZIP compressed
glyph.
(ft_glyphslot_done): Free the document data if it is a GZIP compressed
glyph.
(FT_Load_Glyph): Don't auto-hint SVG documents.
* src/cache/ftcbasic.c (ftc_basic_family_load_glyph): Add support for
FT_GLYPH_FORMAT_SVG.
* src/sfnt/rules.mk (SFNT_DRV_SRC): Add `ttsvg.c`.
* src/sfnt/sfdriver.c: Include `ttsvg.h`.
(sfnt_interface): Add `tt_face_load_svg`, `tt_face_free_svg` and
`tt_face_load_svg_doc`.
* src/sfnt/sfnt.c: Include `ttsvg.c`.
* src/sfnt/sfobjs.c (sfnt_load_face, sfnt_done_face): Add code to load and
free data of the the SVG table.
* src/sfnt/ttsvg.c: New file, implementing `tt_face_load_svg`,
`tt_face_free_svg` and `tt_face_load_svg_doc`.
* src/sfnt/ttsvg.h: Declarations of the SVG functions in
`ttsvg.c`.
Werner Lemberg