tree ada4a33bcda4377cf8f939f2ae2decb145e238f3
parent 40bf722f8064f50200b8c4f8946cd625b441dda9
author Zheyu Ma <zheyuma97@gmail.com> 1659616883 +0800
committer Helge Deller <deller@gmx.de> 1659717854 +0200

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

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@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>