From 2b12582fbf786a34ef11a84b5371f6c8c36ae22d Mon Sep 17 00:00:00 2001
From: Zheyu Ma <zheyuma97@gmail.com>
Date: Mon, 4 Apr 2022 16:47:22 +0800
Subject: video: fbdev: arkfb: Error out if 'pixclock' equals zero
Git-commit: e1e965156438a3662dbb151d892ada834214c833
Patch-mainline: v5.18-rc5
References: jsc#PED-1166 jsc#PED-1168 jsc#PED-1170 jsc#PED-1218 jsc#PED-1220 jsc#PED-1222 jsc#PED-1223 jsc#PED-1225
The userspace program could pass any values to the driver through
ioctl() interface. If the driver doesn't check the value of 'pixclock',
it may cause divide error.
Fix this by checking whether 'pixclock' is zero.
The following log reveals it:
divide error: 0000 [#1] PREEMPT SMP KASAN PTI
RIP: 0010:arkfb_set_par+0x10fc/0x24f0
Call Trace:
<TASK>
fb_set_var+0x604/0xeb0
do_fb_ioctl+0x234/0x670
fb_ioctl+0xdd/0x130
do_syscall_64+0x3b/0x90
Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
Signed-off-by: Helge Deller <deller@gmx.de>
Acked-by: Patrik Jakobsson <pjakobsson@suse.de>
---
drivers/video/fbdev/arkfb.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/video/fbdev/arkfb.c b/drivers/video/fbdev/arkfb.c
index edf169d0816e..eb3e47c58c5f 100644
--- a/drivers/video/fbdev/arkfb.c
+++ b/drivers/video/fbdev/arkfb.c
@@ -566,6 +566,9 @@ static int arkfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
{
int rv, mem, step;
+ if (!var->pixclock)
+ return -EINVAL;
+
/* Find appropriate format */
rv = svga_match_format (arkfb_formats, var, NULL);
if (rv < 0)
--
2.38.1