linux/lib/fonts
Peilin Ye 6735b4632d Fonts: Support FONT_EXTRA_WORDS macros for built-in fonts
syzbot has reported an issue in the framebuffer layer, where a malicious
user may overflow our built-in font data buffers.

In order to perform a reliable range check, subsystems need to know
`FONTDATAMAX` for each built-in font. Unfortunately, our font descriptor,
`struct console_font` does not contain `FONTDATAMAX`, and is part of the
UAPI, making it infeasible to modify it.

For user-provided fonts, the framebuffer layer resolves this issue by
reserving four extra words at the beginning of data buffers. Later,
whenever a function needs to access them, it simply uses the following
macros:

Recently we have gathered all the above macros to <linux/font.h>. Let us
do the same thing for built-in fonts, prepend four extra words (including
`FONTDATAMAX`) to their data buffers, so that subsystems can use these
macros for all fonts, no matter built-in or user-provided.

This patch depends on patch "fbdev, newport_con: Move FONT_EXTRA_WORDS
macros into linux/font.h".

Cc: stable@vger.kernel.org
Link: https://syzkaller.appspot.com/bug?id=08b8be45afea11888776f897895aef9ad1c3ecfd
Signed-off-by: Peilin Ye <yepeilin.cs@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/ef18af00c35fb3cc826048a5f70924ed6ddce95b.1600953813.git.yepeilin.cs@gmail.com
2020-09-25 10:28:51 +02:00
..
font_6x10.c Fonts: Support FONT_EXTRA_WORDS macros for built-in fonts 2020-09-25 10:28:51 +02:00
font_6x11.c Fonts: Support FONT_EXTRA_WORDS macros for built-in fonts 2020-09-25 10:28:51 +02:00
font_7x14.c Fonts: Support FONT_EXTRA_WORDS macros for built-in fonts 2020-09-25 10:28:51 +02:00
font_8x8.c Fonts: Support FONT_EXTRA_WORDS macros for built-in fonts 2020-09-25 10:28:51 +02:00
font_8x16.c Fonts: Support FONT_EXTRA_WORDS macros for built-in fonts 2020-09-25 10:28:51 +02:00
font_10x18.c Fonts: Support FONT_EXTRA_WORDS macros for built-in fonts 2020-09-25 10:28:51 +02:00
font_acorn_8x8.c Fonts: Support FONT_EXTRA_WORDS macros for built-in fonts 2020-09-25 10:28:51 +02:00
font_mini_4x6.c Fonts: Support FONT_EXTRA_WORDS macros for built-in fonts 2020-09-25 10:28:51 +02:00
font_pearl_8x8.c Fonts: Support FONT_EXTRA_WORDS macros for built-in fonts 2020-09-25 10:28:51 +02:00
font_sun8x16.c Fonts: Support FONT_EXTRA_WORDS macros for built-in fonts 2020-09-25 10:28:51 +02:00
font_sun12x22.c Fonts: Support FONT_EXTRA_WORDS macros for built-in fonts 2020-09-25 10:28:51 +02:00
font_ter16x32.c Fonts: Support FONT_EXTRA_WORDS macros for built-in fonts 2020-09-25 10:28:51 +02:00
fonts.c fonts: Prefer a bigger font for high resolution screens 2019-06-20 10:11:24 +02:00
Kconfig treewide: Add SPDX license identifier - Makefile/Kconfig 2019-05-21 10:50:46 +02:00
Makefile Fonts: New Terminus large console font 2018-12-19 10:42:08 +01:00