From: Zheyu Ma zheyuma97@gmail.com
[ 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@gmail.com Signed-off-by: Helge Deller deller@gmx.de Signed-off-by: Sasha Levin sashal@kernel.org --- drivers/video/fbdev/vt8623fb.c | 2 ++ 1 file changed, 2 insertions(+)
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 */