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

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Message-Id: <20250614005646.3117593-1-alexguo1023@gmail.com>
Date: Fri, 13 Jun 2025 20:56:46 -0400
From: Alex Guo <alexguo1023@...il.com>
To: deller@....de
Cc: alexguo1023@...il.com,
	linux-fbdev@...r.kernel.org,
	dri-devel@...ts.freedesktop.org,
	linux-kernel@...r.kernel.org
Subject: [PATCH] fbdev: tdfxfb: Fix potential divide by zero

Variable var->pixclock can be set by user. In case it equals to
zero, divide by zero would occur in tdfxfb_check_var. Similar
crashes have happened in other fbdev drivers. We fix this by
checking whether 'pixclock' is zero.

Signed-off-by: Alex Guo <alexguo1023@...il.com>
---
 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 51ebe78359ec..2100857fa7b3 100644
--- a/drivers/video/fbdev/tdfxfb.c
+++ b/drivers/video/fbdev/tdfxfb.c
@@ -495,6 +495,9 @@ static int tdfxfb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
 			return -EINVAL;
 		}
 	}
+	
+	if (var->pixclock <= KHZ2PICOS(par->max_pixclock))
+		var->pixclock = KHZ2PICOS(par->max_pixclock) + 1;
 
 	if (PICOS2KHZ(var->pixclock) > par->max_pixclock) {
 		DPRINTK("pixclock too high (%ldKHz)\n",
-- 
2.34.1