[PATCH 4.4 068/115] fbdev: controlfb: Add missing modes to fix out of bounds access

Greg Kroah-Hartman
2017-12-18T15:55:17Z

From: Geert Uytterhoeven <geert@linux-m68k.org>

[ Upstream commit ac831a379d34109451b3c41a44a20ee10ecb615f ]

Dan's static analysis says:

drivers/video/fbdev/controlfb.c:560 control_setup()
error: buffer overflow 'control_mac_modes' 20 <= 21

Indeed, control_mac_modes[] has only 20 elements, while VMODE_MAX is 22,
which may lead to an out of bounds read when parsing vmode commandline
options.

The bug was introduced in v2.4.5.6, when 2 new modes were added to
macmodes.h, but control_mac_modes[] wasn't updated:

https://kernel.opensuse.org/cgit/kernel/diff/include/video/macmodes.h?h=v2.5.2&id=29f279c764808560eaceb88fef36cbc35c529aad

Augment control_mac_modes[] with the two new video modes to fix this.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Dan Carpenter <dan.carpenter@oracle.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/video/fbdev/controlfb.h | 2 ++
1 file changed, 2 insertions(+)

--- a/drivers/video/fbdev/controlfb.h
+++ b/drivers/video/fbdev/controlfb.h
@@ -141,5 +141,7 @@ static struct max_cmodes control_mac_mod
{{ 1, 2}}, /* 1152x870, 75Hz */
{{ 0, 1}}, /* 1280x960, 75Hz */
{{ 0, 1}}, /* 1280x1024, 75Hz */
+ {{ 1, 2}}, /* 1152x768, 60Hz */
+ {{ 0, 1}}, /* 1600x1024, 60Hz */
};