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

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Message-Id: <20250614005059.3108265-1-alexguo1023@gmail.com>
Date: Fri, 13 Jun 2025 20:50:59 -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: sstfb: 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 sstfb_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/sstfb.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/video/fbdev/sstfb.c b/drivers/video/fbdev/sstfb.c
index 2ea947f57efb..fd387ca8401b 100644
--- a/drivers/video/fbdev/sstfb.c
+++ b/drivers/video/fbdev/sstfb.c
@@ -359,7 +359,7 @@ static int sstfb_check_var(struct fb_var_screeninfo *var,
 	int tiles_in_X, real_length;
 	unsigned int freq;
 
-	if (sst_calc_pll(PICOS2KHZ(var->pixclock), &freq, &par->pll)) {
+	if (var->pixclock && sst_calc_pll(PICOS2KHZ(var->pixclock), &freq, &par->pll)) {
 		printk(KERN_ERR "sstfb: Pixclock at %ld KHZ out of range\n",
 				PICOS2KHZ(var->pixclock));
 		return -EINVAL;
-- 
2.34.1