Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit d71528cc authored by Zheyu Ma's avatar Zheyu Ma Committed by Greg Kroah-Hartman
Browse files

video: fbdev: vt8623fb: Check the size of screen before memset_io() 



[ Upstream commit ec0754c60217248fa77cc9005d66b2b55200ac06 ]

In the function vt8623fb_set_par(), the value of 'screen_size' is
calculated by the user input. If the user provides the improper value,
the value of 'screen_size' may larger than 'info->screen_size', which
may cause the following bug:

[  583.339036] BUG: unable to handle page fault for address: ffffc90005000000
[  583.339049] #PF: supervisor write access in kernel mode
[  583.339052] #PF: error_code(0x0002) - not-present page
[  583.339074] RIP: 0010:memset_orig+0x33/0xb0
[  583.339110] Call Trace:
[  583.339118]  vt8623fb_set_par+0x11cd/0x21e0
[  583.339146]  fb_set_var+0x604/0xeb0
[  583.339181]  do_fb_ioctl+0x234/0x670
[  583.339209]  fb_ioctl+0xdd/0x130

Fix the this by checking the value of 'screen_size' before memset_io().

Fixes: 558b7bd8 ("vt8623fb: new framebuffer driver for VIA VT8623")
Signed-off-by: default avatarZheyu Ma <zheyuma97@gmail.com>
Signed-off-by: default avatarHelge Deller <deller@gmx.de>
Signed-off-by: default avatarSasha Levin <sashal@kernel.org>
parent 09777c16

drivers/video/fbdev/vt8623fb.c

+2 −0
Original line number Diff line number Diff line
@@ -504,6 +504,8 @@ static int vt8623fb_set_par(struct fb_info *info) 
			 (info->var.vmode & FB_VMODE_DOUBLE) ? 2 : 1, 1,

			 1, info->node);



	if (screen_size > info->screen_size)

		screen_size = info->screen_size;

	memset_io(info->screen_base, 0x00, screen_size);



	/* Device and screen back on */