linux-kernel - [PATCH 4.9 120/175] video: fbdev: kyro: Error out if pixclock equals zero

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <20210920163922.002639494@linuxfoundation.org>
Date:   Mon, 20 Sep 2021 18:42:49 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Zheyu Ma <zheyuma97@...il.com>,
        Sam Ravnborg <sam@...nborg.org>,
        Sasha Levin <sashal@...nel.org>
Subject: [PATCH 4.9 120/175] video: fbdev: kyro: Error out if pixclock equals zero

From: Zheyu Ma <zheyuma97@...il.com>

[ Upstream commit 1520b4b7ba964f8eec2e7dd14c571d50de3e5191 ]

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 because the value of 'lineclock' and
'frameclock' will be zero.

Fix this by checking whether 'pixclock' is zero in kyrofb_check_var().

The following log reveals it:

[  103.073930] divide error: 0000 [#1] PREEMPT SMP KASAN PTI
[  103.073942] CPU: 4 PID: 12483 Comm: syz-executor Not tainted 5.14.0-rc2-00478-g2734d6c1b1a0-dirty #118
[  103.073959] RIP: 0010:kyrofb_set_par+0x316/0xc80
[  103.074045] Call Trace:
[  103.074048]  ? ___might_sleep+0x1ee/0x2d0
[  103.074060]  ? kyrofb_ioctl+0x330/0x330
[  103.074069]  fb_set_var+0x5bf/0xeb0
[  103.074078]  ? fb_blank+0x1a0/0x1a0
[  103.074085]  ? lock_acquire+0x3bd/0x530
[  103.074094]  ? lock_release+0x810/0x810
[  103.074103]  ? ___might_sleep+0x1ee/0x2d0
[  103.074114]  ? __mutex_lock+0x620/0x1190
[  103.074126]  ? trace_hardirqs_on+0x6a/0x1c0
[  103.074137]  do_fb_ioctl+0x31e/0x700
[  103.074144]  ? fb_getput_cmap+0x280/0x280
[  103.074152]  ? rcu_read_lock_sched_held+0x11/0x80
[  103.074162]  ? rcu_read_lock_sched_held+0x11/0x80
[  103.074171]  ? __sanitizer_cov_trace_switch+0x67/0xf0
[  103.074181]  ? __sanitizer_cov_trace_const_cmp2+0x20/0x80
[  103.074191]  ? do_vfs_ioctl+0x14b/0x16c0
[  103.074199]  ? vfs_fileattr_set+0xb60/0xb60
[  103.074207]  ? rcu_read_lock_sched_held+0x11/0x80
[  103.074216]  ? lock_release+0x483/0x810
[  103.074224]  ? __fget_files+0x217/0x3d0
[  103.074234]  ? __fget_files+0x239/0x3d0
[  103.074243]  ? do_fb_ioctl+0x700/0x700
[  103.074250]  fb_ioctl+0xe6/0x130

Signed-off-by: Zheyu Ma <zheyuma97@...il.com>
Signed-off-by: Sam Ravnborg <sam@...nborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1627293835-17441-3-git-send-email-zheyuma97@gmail.com
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/video/fbdev/kyro/fbdev.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/video/fbdev/kyro/fbdev.c b/drivers/video/fbdev/kyro/fbdev.c
index 517057a48dd4..0b844f6d8a30 100644
--- a/drivers/video/fbdev/kyro/fbdev.c
+++ b/drivers/video/fbdev/kyro/fbdev.c
@@ -399,6 +399,9 @@ static int kyrofb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
 {
 	struct kyrofb_info *par = info->par;
 
+	if (!var->pixclock)
+		return -EINVAL;
+
 	if (var->bits_per_pixel != 16 && var->bits_per_pixel != 32) {
 		printk(KERN_WARNING "kyrofb: depth not supported: %u\n", var->bits_per_pixel);
 		return -EINVAL;
-- 
2.30.2