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

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Date:   Thu, 16 Mar 2023 14:34:42 +0100
From:   Helge Deller <deller@....de>
To:     Wei Chen <harperchen1110@...il.com>, adaplas@...il.com
Cc:     linux-fbdev@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH] fbdev: nvidia: Fix potential divide by zero

On 3/15/23 08:18, Wei Chen wrote:
> 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>

applied all four patches.

Thanks!
Helge

> ---
>   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;