From 763b7d95ba97ed8f6994c4e8136c9835027baf36 Mon Sep 17 00:00:00 2001
From: Zheyu Ma <zheyuma97@gmail.com>
Date: Mon, 4 Apr 2022 16:47:17 +0800
Subject: video: fbdev: i740fb: Error out if 'pixclock' equals zero
Git-commit: 15cf0b82271b1823fb02ab8c377badba614d95d5
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
i740fb_check_var().
The following log reveals it:
divide error: 0000 [#1] PREEMPT SMP KASAN PTI
RIP: 0010:i740fb_decode_var drivers/video/fbdev/i740fb.c:444 [inline]
RIP: 0010:i740fb_set_par+0x272f/0x3bb0 drivers/video/fbdev/i740fb.c:739
Call Trace:
fb_set_var+0x604/0xeb0 drivers/video/fbdev/core/fbmem.c:1036
do_fb_ioctl+0x234/0x670 drivers/video/fbdev/core/fbmem.c:1112
fb_ioctl+0xdd/0x130 drivers/video/fbdev/core/fbmem.c:1191
vfs_ioctl fs/ioctl.c:51 [inline]
__do_sys_ioctl fs/ioctl.c:874 [inline]
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/i740fb.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/video/fbdev/i740fb.c b/drivers/video/fbdev/i740fb.c
index dd45ea8203be..09dd85553d4f 100644
--- a/drivers/video/fbdev/i740fb.c
+++ b/drivers/video/fbdev/i740fb.c
@@ -657,6 +657,9 @@ static int i740fb_decode_var(const struct fb_var_screeninfo *var,
static int i740fb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
{
+ if (!var->pixclock)
+ return -EINVAL;
+
switch (var->bits_per_pixel) {
case 8:
var->red.offset = var->green.offset = var->blue.offset = 0;
--
2.38.1