linux-kernel - [PATCH AUTOSEL 5.4 7/9] fbdev: intelfb: Fix potential divide by zero

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Message-Id: <20230322200242.1997527-7-sashal@kernel.org>
Date:   Wed, 22 Mar 2023 16:02:39 -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>, mbroemme@...mpq.org,
        linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org
Subject: [PATCH AUTOSEL 5.4 7/9] fbdev: intelfb: Fix potential divide by zero

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

[ Upstream commit d823685486a3446d061fed7c7d2f80af984f119a ]

Variable var->pixclock is controlled by user and can be assigned
to zero. Without proper check, divide by zero would occur in
intelfbhw_validate_mode and intelfbhw_mode_to_hw.

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/intelfb/intelfbdrv.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/video/fbdev/intelfb/intelfbdrv.c b/drivers/video/fbdev/intelfb/intelfbdrv.c
index a76c61512c608..274e6bb4a9610 100644
--- a/drivers/video/fbdev/intelfb/intelfbdrv.c
+++ b/drivers/video/fbdev/intelfb/intelfbdrv.c
@@ -1214,6 +1214,9 @@ static int intelfb_check_var(struct fb_var_screeninfo *var,
 
 	dinfo = GET_DINFO(info);
 
+	if (!var->pixclock)
+		return -EINVAL;
+
 	/* update the pitch */
 	if (intelfbhw_validate_mode(dinfo, var) != 0)
 		return -EINVAL;
-- 
2.39.2