linux-kernel - [PATCH AUTOSEL 4.19 8/9] fbdev: lxfb: Fix potential divide by zero

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Message-Id: <20230322200309.1997651-8-sashal@kernel.org>
Date:   Wed, 22 Mar 2023 16:03:08 -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>, dilinger@...ued.net,
        linux-geode@...ts.infradead.org, linux-fbdev@...r.kernel.org,
        dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 4.19 8/9] fbdev: lxfb: Fix potential divide by zero

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

[ Upstream commit 61ac4b86a4c047c20d5cb423ddd87496f14d9868 ]

var->pixclock can be assigned to zero by user. Without proper
check, divide by zero would occur in lx_set_clock.

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/geode/lxfb_core.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/video/fbdev/geode/lxfb_core.c b/drivers/video/fbdev/geode/lxfb_core.c
index 138da6cb6cbcd..4345246b4c798 100644
--- a/drivers/video/fbdev/geode/lxfb_core.c
+++ b/drivers/video/fbdev/geode/lxfb_core.c
@@ -247,6 +247,9 @@ static void get_modedb(struct fb_videomode **modedb, unsigned int *size)
 
 static int lxfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
 {
+	if (!var->pixclock)
+		return -EINVAL;
+
 	if (var->xres > 1920 || var->yres > 1440)
 		return -EINVAL;
 
-- 
2.39.2