[sfnt] Fix bounds check in SVG.

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
This commit is contained in:
Ben Wagner 2022-03-03 16:33:40 -05:00
parent 034e5dbf92
commit 335224beee

View File

@ -39,11 +39,11 @@
/* NOTE: These table sizes are given by the specification. */
#define SVG_TABLE_HEADER_SIZE 10U
#define SVG_DOCUMENT_RECORD_SIZE 12U
#define SVG_DOCUMENT_LIST_MINIMUM_SIZE 2U + SVG_DOCUMENT_RECORD_SIZE
#define SVG_MINIMUM_SIZE SVG_TABLE_HEADER_SIZE + \
SVG_DOCUMENT_LIST_MINIMUM_SIZE
#define SVG_TABLE_HEADER_SIZE (10U)
#define SVG_DOCUMENT_RECORD_SIZE (12U)
#define SVG_DOCUMENT_LIST_MINIMUM_SIZE (2U + SVG_DOCUMENT_RECORD_SIZE)
#define SVG_MINIMUM_SIZE (SVG_TABLE_HEADER_SIZE + \
SVG_DOCUMENT_LIST_MINIMUM_SIZE)
typedef struct Svg_