linux-kernel - Re: [PATCH] iio: hmc: fix a potential NULL pointer dereference

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Message-ID: <20190309134208.GA7820@arch>
Date:   Sat, 9 Mar 2019 14:42:09 +0100
From:   Tomasz Duszynski <tduszyns@...il.com>
To:     Kangjie Lu <kjlu@....edu>
Cc:     pakki001@....edu, Jonathan Cameron <jic23@...nel.org>,
        Hartmut Knaack <knaack.h@....de>,
        Lars-Peter Clausen <lars@...afoo.de>,
        Peter Meerwald-Stadler <pmeerw@...erw.net>,
        linux-iio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] iio: hmc: fix a potential NULL pointer dereference

On Fri, Mar 08, 2019 at 11:15:32PM -0600, Kangjie Lu wrote:
> devm_regmap_init_i2c may fail and return NULL. The fix returns
> the error when it fails.
>
> Signed-off-by: Kangjie Lu <kjlu@....edu>
> ---
>  drivers/iio/magnetometer/hmc5843_i2c.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/iio/magnetometer/hmc5843_i2c.c b/drivers/iio/magnetometer/hmc5843_i2c.c
> index 3de7f4426ac4..c0cd0823f8d5 100644
> --- a/drivers/iio/magnetometer/hmc5843_i2c.c
> +++ b/drivers/iio/magnetometer/hmc5843_i2c.c
> @@ -58,8 +58,13 @@ static const struct regmap_config hmc5843_i2c_regmap_config = {
>  static int hmc5843_i2c_probe(struct i2c_client *cli,
>  			     const struct i2c_device_id *id)
>  {
> +	struct regmap *devm_regmap = devm_regmap_init_i2c(cli,
> +			&hmc5843_i2c_regmap_config);
> +	if (IS_ERR(devm_regmap))
> +		return PTR_ERR(devm_regmap);

This fixes only one part of the problem leaving identical spi issue
behind. I guess this check should be part of *common_probe().

> +
>  	return hmc5843_common_probe(&cli->dev,
> -			devm_regmap_init_i2c(cli, &hmc5843_i2c_regmap_config),
> +			devm_regmap,
>  			id->driver_data, id->name);
>  }
>
> --
> 2.17.1
>