From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Zheyu Ma <zheyuma97@gmail.com>, Sam Ravnborg <sam@ravnborg.org>,
Sasha Levin <sashal@kernel.org>,
dri-devel@lists.freedesktop.org, linux-fbdev@vger.kernel.org
Subject: [PATCH AUTOSEL 4.9 15/48] video: fbdev: asiliantfb: Error out if 'pixclock' equals zero
Date: Thu, 9 Sep 2021 07:59:42 -0400 [thread overview]
Message-ID: <20210909120015.150411-15-sashal@kernel.org> (raw)
In-Reply-To: <20210909120015.150411-1-sashal@kernel.org>
From: Zheyu Ma <zheyuma97@gmail.com>
[ Upstream commit b36b242d4b8ea178f7fd038965e3cac7f30c3f09 ]
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 first.
The following log reveals it:
[ 43.861711] divide error: 0000 [#1] PREEMPT SMP KASAN PTI
[ 43.861737] CPU: 2 PID: 11764 Comm: i740 Not tainted 5.14.0-rc2-00513-gac532c9bbcfb-dirty #224
[ 43.861756] RIP: 0010:asiliantfb_check_var+0x4e/0x730
[ 43.861843] Call Trace:
[ 43.861848] ? asiliantfb_remove+0x190/0x190
[ 43.861858] fb_set_var+0x2e4/0xeb0
[ 43.861866] ? fb_blank+0x1a0/0x1a0
[ 43.861873] ? lock_acquire+0x1ef/0x530
[ 43.861884] ? lock_release+0x810/0x810
[ 43.861892] ? lock_is_held_type+0x100/0x140
[ 43.861903] ? ___might_sleep+0x1ee/0x2d0
[ 43.861914] ? __mutex_lock+0x620/0x1190
[ 43.861921] ? do_fb_ioctl+0x313/0x700
[ 43.861929] ? mutex_lock_io_nested+0xfa0/0xfa0
[ 43.861936] ? __this_cpu_preempt_check+0x1d/0x30
[ 43.861944] ? _raw_spin_unlock_irqrestore+0x46/0x60
[ 43.861952] ? lockdep_hardirqs_on+0x59/0x100
[ 43.861959] ? _raw_spin_unlock_irqrestore+0x46/0x60
[ 43.861967] ? trace_hardirqs_on+0x6a/0x1c0
[ 43.861978] do_fb_ioctl+0x31e/0x700
Signed-off-by: Zheyu Ma <zheyuma97@gmail.com>
Signed-off-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/1627293835-17441-2-git-send-email-zheyuma97@gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/video/fbdev/asiliantfb.c | 3 +++
1 file changed, 3 insertions(+)
diff --git a/drivers/video/fbdev/asiliantfb.c b/drivers/video/fbdev/asiliantfb.c
index 91eea4583382..ceb579eff1ea 100644
--- a/drivers/video/fbdev/asiliantfb.c
+++ b/drivers/video/fbdev/asiliantfb.c
@@ -227,6 +227,9 @@ static int asiliantfb_check_var(struct fb_var_screeninfo *var,
{
unsigned long Ftarget, ratio, remainder;
+ if (!var->pixclock)
+ return -EINVAL;
+
ratio = 1000000 / var->pixclock;
remainder = 1000000 % var->pixclock;
Ftarget = 1000000 * ratio + (1000000 * remainder) / var->pixclock;
--
2.30.2
next prev parent reply other threads:[~2021-09-09 13:11 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20210909120015.150411-1-sashal@kernel.org>
2021-09-09 11:59 ` [PATCH AUTOSEL 4.9 04/48] video: fbdev: kyro: fix a DoS bug by restricting user input Sasha Levin
2021-09-09 11:59 ` Sasha Levin [this message]
2021-09-09 11:59 ` [PATCH AUTOSEL 4.9 16/48] video: fbdev: kyro: Error out if 'pixclock' equals zero Sasha Levin
2021-09-09 11:59 ` [PATCH AUTOSEL 4.9 17/48] video: fbdev: riva: " Sasha Levin
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