linux-kernel - Re: [PATCH] Mfd - Fix possible NULL derefrence.

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Date:   Tue, 7 Feb 2017 16:32:21 +0000
From:   Lee Jones <lee.jones@...aro.org>
To:     Shailendra Verma <shailendra.v@...sung.com>
Cc:     linux-kernel@...r.kernel.org, p.shailesh@...sung.com,
        ashish.kalra@...sung.com,
        Shailendra Verma <shailendra.capricorn@...il.com>
Subject: Re: [PATCH] Mfd - Fix possible NULL derefrence.

On Fri, 27 Jan 2017, Shailendra Verma wrote:

> of_match_device could return NULL, and so can cause a NULL
> pointer dereference later.

I don't think it can.

Did this actually happen to you?

> Signed-off-by: Shailendra Verma <shailendra.v@...sung.com>
> ---
>  drivers/mfd/mc13xxx-i2c.c |    4 ++++
>  drivers/mfd/mc13xxx-spi.c |    5 ++++-
>  2 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/mfd/mc13xxx-i2c.c b/drivers/mfd/mc13xxx-i2c.c
> index 67e4c9a..e03f454 100644
> --- a/drivers/mfd/mc13xxx-i2c.c
> +++ b/drivers/mfd/mc13xxx-i2c.c
> @@ -80,6 +80,10 @@ static int mc13xxx_i2c_probe(struct i2c_client *client,
>  	if (client->dev.of_node) {
>  		const struct of_device_id *of_id =
>  			of_match_device(mc13xxx_dt_ids, &client->dev);
> +		if (!of_id) {
> +			dev_err(&client->dev, "Error: No device match found\n");
> +			return -ENODEV;
> +		}
>  		mc13xxx->variant = of_id->data;
>  	} else {
>  		mc13xxx->variant = (void *)id->driver_data;
> diff --git a/drivers/mfd/mc13xxx-spi.c b/drivers/mfd/mc13xxx-spi.c
> index cbc1e5e..97ab19c 100644
> --- a/drivers/mfd/mc13xxx-spi.c
> +++ b/drivers/mfd/mc13xxx-spi.c
> @@ -157,7 +157,10 @@ static int mc13xxx_spi_probe(struct spi_device *spi)
>  	if (spi->dev.of_node) {
>  		const struct of_device_id *of_id =
>  			of_match_device(mc13xxx_dt_ids, &spi->dev);
> +		if (!of_id) {
> +			dev_err(&spi->dev, "Error: No device match found\n");
> +			return -ENODEV;
> +		}
>  		mc13xxx->variant = of_id->data;
>  	} else {
>  		const struct spi_device_id *id_entry = spi_get_device_id(spi);

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