linux-kernel - Re: [PATCH] ad7780: fix division by zero in ad7780_write

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Message-ID: <20241031210853.4a0bc3a9@jic23-huawei>
Date: Thu, 31 Oct 2024 21:08:53 +0000
From: Jonathan Cameron <jic23@...nel.org>
To: Zicheng Qu <quzicheng@...wei.com>
Cc: <Michael.Hennerich@...log.com>, <renatogeh@...il.com>,
 <lars@...afoo.de>, <giuliano.belinassi@....br>,
 <linux-iio@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
 <tanghui20@...wei.com>, <zhangqiao22@...wei.com>, <judy.chenhui@...wei.com>
Subject: Re: [PATCH] ad7780: fix division by zero in ad7780_write_raw()

On Mon, 28 Oct 2024 14:20:27 +0000
Zicheng Qu <quzicheng@...wei.com> wrote:

> In the ad7780_write_raw() , val2 can be zero, which might lead to a
> division by zero error in DIV_ROUND_CLOSEST(). The ad7780_write_raw()
> is based on iio_info's write_raw. While val is explicitly declared that
> can be zero (in read mode), val2 is not specified to be non-zero.
> 
> Fixes: 9085daa4abcc ("staging: iio: ad7780: add gain & filter gpio support")
> Cc: <stable@...r.kernel.org>
> Signed-off-by: Zicheng Qu <quzicheng@...wei.com>
Applied to the fixes-togreg branch of iio.git.

I might end up dragging this in to my queue for the coming merge window
if I don't get time to do another fixes pull request in the next few
days.

Jonathan

> ---
>  drivers/iio/adc/ad7780.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/iio/adc/ad7780.c b/drivers/iio/adc/ad7780.c
> index e9b0c577c9cc..8ccb74f47030 100644
> --- a/drivers/iio/adc/ad7780.c
> +++ b/drivers/iio/adc/ad7780.c
> @@ -152,7 +152,7 @@ static int ad7780_write_raw(struct iio_dev *indio_dev,
>  
>  	switch (m) {
>  	case IIO_CHAN_INFO_SCALE:
> -		if (val != 0)
> +		if (val != 0 || val2 == 0)
>  			return -EINVAL;
>  
>  		vref = st->int_vref_mv * 1000000LL;