From 73692342f9ee752fdb55f32b41404d8ff61dfee5 Mon Sep 17 00:00:00 2001
From: Zheyu Ma <zheyuma97@gmail.com>
Date: Mon, 4 Apr 2022 16:47:20 +0800
Subject: video: fbdev: vt8623fb: Error out if 'pixclock' equals zero
Git-commit: f2bfd792c1ed4b1e0578db3fcdb0879dc87fe027
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 in the function
vt8623fb_check_var().
The following log reveals it:
divide error: 0000 [#1] PREEMPT SMP KASAN PTI
RIP: 0010:vt8623fb_set_par+0xecd/0x2210
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/vt8623fb.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/video/fbdev/vt8623fb.c b/drivers/video/fbdev/vt8623fb.c
index 7a959e5ba90b..a92a8c670cf0 100644
--- a/drivers/video/fbdev/vt8623fb.c
+++ b/drivers/video/fbdev/vt8623fb.c
@@ -321,6 +321,9 @@ static int vt8623fb_check_var(struct fb_var_screeninfo *var, struct fb_info *inf
{
int rv, mem, step;
+ if (!var->pixclock)
+ return -EINVAL;
+
/* Find appropriate format */
rv = svga_match_format (vt8623fb_formats, var, NULL);
if (rv < 0)
--
2.38.1