From 14767d5b621715348e5ba8fde439a2aaba7df178 Mon Sep 17 00:00:00 2001
From: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Date: Thu, 9 Apr 2026 15:23:14 +0200
Subject: [PATCH] fbdev: tdfxfb: avoid divide-by-zero on FBIOPUT_VSCREENINFO

commit 8f98b81fe011e1879e6a7b1247e69e06a5e17af2 upstream.

Much like commit 19f953e74356 ("fbdev: fb_pm2fb: Avoid potential divide
by zero error"), we also need to prevent that same crash from happening
in the udlfb driver as it uses pixclock directly when dividing, which
will crash.

Cc: Helge Deller <deller@gmx.de>
Assisted-by: gregkh_clanker_t1000
Cc: stable <stable@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Helge Deller <deller@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ulrich Hecht <uli@kernel.org>
---
 drivers/video/fbdev/tdfxfb.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/video/fbdev/tdfxfb.c b/drivers/video/fbdev/tdfxfb.c
index fbbf26b170f7..bb31e3a61ced 100644
--- a/drivers/video/fbdev/tdfxfb.c
+++ b/drivers/video/fbdev/tdfxfb.c
@@ -496,6 +496,9 @@ static int tdfxfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
 		}
 	}
 
+	if (!var->pixclock)
+		return -EINVAL;
+
 	if (PICOS2KHZ(var->pixclock) > par->max_pixclock) {
 		DPRINTK("pixclock too high (%ldKHz)\n",
 			PICOS2KHZ(var->pixclock));