linux-kernel - [PATCH] fbdev: intelfb: Fix potential divide by zero

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Date:   Wed, 15 Mar 2023 08:33:47 +0000
From:   Wei Chen <harperchen1110@...il.com>
To:     mbroemme@...mpq.org
Cc:     deller@....de, linux-fbdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, Wei Chen <harperchen1110@...il.com>
Subject: [PATCH] fbdev: intelfb: Fix potential divide by zero

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>
---
 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 0a9e5067b201..a81095b2b1ea 100644
--- a/drivers/video/fbdev/intelfb/intelfbdrv.c
+++ b/drivers/video/fbdev/intelfb/intelfbdrv.c
@@ -1222,6 +1222,9 @@ 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;
-- 
2.25.1