This is a note to let you know that I've just added the patch titled
video: fbdev: vt8623fb: Check the size of screen before memset_io()
to the 4.14-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
video-fbdev-vt8623fb-check-the-size-of-screen-before.patch
and it can be found in the queue-4.14 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit a09b4f6cfd10b042ab5fe6f5b577e0368fe27a17
Author: Zheyu Ma <zheyuma97@xxxxxxxxx>
Date: Thu Aug 4 20:41:23 2022 +0800
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: 558b7bd86c32 ("vt8623fb: new framebuffer driver for VIA VT8623")
Signed-off-by: Zheyu Ma <zheyuma97@xxxxxxxxx>
Signed-off-by: Helge Deller <deller@xxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/video/fbdev/vt8623fb.c b/drivers/video/fbdev/vt8623fb.c
index 5cac871db3ee..cbae9c510092 100644
--- a/drivers/video/fbdev/vt8623fb.c
+++ b/drivers/video/fbdev/vt8623fb.c
@@ -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 */
