linux-kernel - Re: [PATCH] iio: adc: imx25-gcq: Variable could be uninitialized if regmap

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Date:   Mon, 30 Sep 2019 09:44:12 +0200
From:   Marco Felsch <m.felsch@...gutronix.de>
To:     Yizhuo <yzhai003@....edu>
Cc:     csong@...ucr.edu, Kate Stewart <kstewart@...uxfoundation.org>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Pengutronix Kernel Team <kernel@...gutronix.de>,
        Allison Randal <allison@...utok.net>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Enrico Weigelt <info@...ux.net>,
        Fabio Estevam <festevam@...il.com>,
        Sascha Hauer <s.hauer@...gutronix.de>, zhiyunq@...ucr.edu,
        linux-kernel@...r.kernel.org, linux-iio@...r.kernel.org,
        NXP Linux Team <linux-imx@....com>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        Hartmut Knaack <knaack.h@....de>,
        Thomas Gleixner <tglx@...utronix.de>,
        Shawn Guo <shawnguo@...nel.org>,
        Jonathan Cameron <jic23@...nel.org>,
        linux-arm-kernel@...ts.infradead.org
Subject: Re: [PATCH] iio: adc: imx25-gcq: Variable could be uninitialized if
 regmap_read() fails

Hi Yizhuo,

thanks for your patch.

On 19-09-27 17:28, Yizhuo wrote:
> In function mx25_gcq_irq(), local variable "stats" could
> be uninitialized if function regmap_read() returns -EINVAL.
> However, this value is used in if statement, which is
> potentially unsafe. The same case applied to the variable
> "data" in function mx25_gcq_get_raw_value() in the same file.

IMHO the commit header should be something like: "iio: adc: imx25-gcq:
fix uninitialized variable usage"...

and please add a fixes tag.

> 
> Signed-off-by: Yizhuo <yzhai003@....edu>
> ---
>  drivers/iio/adc/fsl-imx25-gcq.c | 10 ++++++++--
>  1 file changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/iio/adc/fsl-imx25-gcq.c b/drivers/iio/adc/fsl-imx25-gcq.c
> index df19ecae52f7..dbf3e8e85aba 100644
> --- a/drivers/iio/adc/fsl-imx25-gcq.c
> +++ b/drivers/iio/adc/fsl-imx25-gcq.c
> @@ -74,7 +74,10 @@ static irqreturn_t mx25_gcq_irq(int irq, void *data)
>  	struct mx25_gcq_priv *priv = data;
>  	u32 stats;
>  
> -	regmap_read(priv->regs, MX25_ADCQ_SR, &stats);
> +	int ret = regmap_read(priv->regs, MX25_ADCQ_SR, &stats);

Please don't do this. First declare the variable and then use it.

Regards,
  Marco

> +
> +	if (ret)
> +		return ret;
>  
>  	if (stats & MX25_ADCQ_SR_EOQ) {
>  		regmap_update_bits(priv->regs, MX25_ADCQ_MR,
> @@ -121,7 +124,10 @@ static int mx25_gcq_get_raw_value(struct device *dev,
>  		return -ETIMEDOUT;
>  	}
>  
> -	regmap_read(priv->regs, MX25_ADCQ_FIFO, &data);
> +	int ret = regmap_read(priv->regs, MX25_ADCQ_FIFO, &data);
> +
> +	if (ret)
> +		return ret;
>  
>  	*val = MX25_ADCQ_FIFO_DATA(data);
>  
> -- 
> 2.17.1
> 
> 
> 

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