linux-kernel - [PATCH AUTOSEL 4.14 9/9] fbdev: au1200fb: Fix potential divide by zero

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Message-Id: <20230322200337.1997810-9-sashal@kernel.org>
Date:   Wed, 22 Mar 2023 16:03:36 -0400
From:   Sasha Levin <sashal@...nel.org>
To:     linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:     Wei Chen <harperchen1110@...il.com>, Helge Deller <deller@....de>,
        Sasha Levin <sashal@...nel.org>, linux-fbdev@...r.kernel.org,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 4.14 9/9] fbdev: au1200fb: Fix potential divide by zero

From: Wei Chen <harperchen1110@...il.com>

[ Upstream commit 44a3b36b42acfc433aaaf526191dd12fbb919fdb ]

var->pixclock can be assigned to zero by user. Without
proper check, divide by zero would occur when invoking
macro PICOS2KHZ in au1200fb_fb_check_var.

Error out if var->pixclock is zero.

Signed-off-by: Wei Chen <harperchen1110@...il.com>
Signed-off-by: Helge Deller <deller@....de>
Signed-off-by: Sasha Levin <sashal@...nel.org>
---
 drivers/video/fbdev/au1200fb.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/video/fbdev/au1200fb.c b/drivers/video/fbdev/au1200fb.c
index 6c542d0ca076e..e17a083f849ad 100644
--- a/drivers/video/fbdev/au1200fb.c
+++ b/drivers/video/fbdev/au1200fb.c
@@ -1039,6 +1039,9 @@ static int au1200fb_fb_check_var(struct fb_var_screeninfo *var,
 	u32 pixclock;
 	int screen_size, plane;
 
+	if (!var->pixclock)
+		return -EINVAL;
+
 	plane = fbdev->plane;
 
 	/* Make sure that the mode respect all LCD controller and
-- 
2.39.2