linux-kernel - Re: [PATCH] mfd: add null check before pointer dereference

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Message-ID: <20170524084317.6fpuedrepvnj62ch@dell>
Date:   Wed, 24 May 2017 09:43:17 +0100
From:   Lee Jones <lee.jones@...aro.org>
To:     "Gustavo A. R. Silva" <garsilva@...eddedor.com>
Cc:     Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>,
        patches@...nsource.wolfsonmicro.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] mfd: add null check before pointer dereference

Please use the $SUBJECT line expected by the subsystem.

The following command can help with this:

  `git log --oneline -- <SUBSYSTEM>`

> Add null check before dereferencing pointer of_id in order to avoid
> a potential NULL pointer dereference.
> 
> Addresses-Coverity-ID: 1408830
> Cc: Charles Keepax <ckeepax@...nsource.wolfsonmicro.com>
> Signed-off-by: Gustavo A. R. Silva <garsilva@...eddedor.com>
> ---
>  drivers/mfd/wm831x-spi.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/mfd/wm831x-spi.c b/drivers/mfd/wm831x-spi.c
> index c332e28..7b227c9 100644
> --- a/drivers/mfd/wm831x-spi.c
> +++ b/drivers/mfd/wm831x-spi.c
> @@ -34,6 +34,10 @@ static int wm831x_spi_probe(struct spi_device *spi)
>  
>  	if (spi->dev.of_node) {
>  		of_id = of_match_device(wm831x_of_match, &spi->dev);
> +		if (!of_id) {
> +			dev_err(&spi->dev, "Failed to find matching id\n");
> +			return -EINVAL;
> +		}

I already mentioned why this isn't suitable.

Please see my pre-review.

>  		type = (enum wm831x_parent)of_id->data;
>  	} else {
>  		type = (enum wm831x_parent)id->driver_data;

-- 
Lee Jones
Linaro STMicroelectronics Landing Team Lead
Linaro.org │ Open source software for ARM SoCs
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