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

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Message-Id: <20230315071831.3833948-1-harperchen1110@gmail.com>
Date:   Wed, 15 Mar 2023 07:18:31 +0000
From:   Wei Chen <harperchen1110@...il.com>
To:     adaplas@...il.com
Cc:     deller@....de, linux-fbdev@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-kernel@...r.kernel.org,
        Wei Chen <harperchen1110@...il.com>
Subject: [PATCH] fbdev: nvidia: 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 nvidiafb_set_par.

Similar crashes have happened in other fbdev drivers. There
is no check and modification on var->pixclock along the call
chain to nvidia_check_var and nvidiafb_set_par. We believe it
could also be triggered in driver nvidia from user site.

Signed-off-by: Wei Chen <harperchen1110@...il.com>
---
 drivers/video/fbdev/nvidia/nvidia.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/video/fbdev/nvidia/nvidia.c b/drivers/video/fbdev/nvidia/nvidia.c
index e60a276b4855..ea4ba3dfb96b 100644
--- a/drivers/video/fbdev/nvidia/nvidia.c
+++ b/drivers/video/fbdev/nvidia/nvidia.c
@@ -764,6 +764,8 @@ static int nvidiafb_check_var(struct fb_var_screeninfo *var,
 	int pitch, err = 0;
 
 	NVTRACE_ENTER();
+	if (!var->pixclock)
+		return -EINVAL;
 
 	var->transp.offset = 0;
 	var->transp.length = 0;
-- 
2.25.1