linux-kernel - Re: [PATCH][V2][next] regulator: axp20x: check rdev is null before dereferencing it

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Message-ID: <20190204193042.GD2563@kadam>
Date:   Mon, 4 Feb 2019 22:30:42 +0300
From:   Dan Carpenter <dan.carpenter@...cle.com>
To:     Colin Ian King <colin.king@...onical.com>
Cc:     Liam Girdwood <lgirdwood@...il.com>,
        Mark Brown <broonie@...nel.org>, Chen-Yu Tsai <wens@...e.org>,
        kernel-janitors@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH][V2][next] regulator: axp20x: check rdev is null before
 dereferencing it

On Mon, Feb 04, 2019 at 07:13:30PM +0000, Colin Ian King wrote:
> >  drivers/regulator/axp20x-regulator.c | 8 ++++++--
> >  1 file changed, 6 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/regulator/axp20x-regulator.c b/drivers/regulator/axp20x-regulator.c
> > index 48af859fd053..0dfa4ea6bbdf 100644
> > --- a/drivers/regulator/axp20x-regulator.c
> > +++ b/drivers/regulator/axp20x-regulator.c
> > @@ -367,7 +367,7 @@ static const int axp209_dcdc2_ldo3_slew_rates[] = {
> >  static int axp20x_set_ramp_delay(struct regulator_dev *rdev, int ramp)
> >  {
> >  	struct axp20x_dev *axp20x = rdev_get_drvdata(rdev);
> > -	const struct regulator_desc *desc = rdev->desc;
> > +	const struct regulator_desc *desc;

This is only called from set_machine_constraints() so "rdev" can't be
NULL.  (On my allmodonconfig build).

> >  	u8 reg, mask, enable, cfg = 0xff;
> >  	const int *slew_rates;
> >  	int rate_count = 0;
> > @@ -375,6 +375,8 @@ static int axp20x_set_ramp_delay(struct regulator_dev *rdev, int ramp)
> >  	if (!rdev)
> >  		return -EINVAL;
> >  
> > +	desc = rdev->desc;
> > +
> >  	switch (axp20x->variant) {
> >  	case AXP209_ID:
> >  		if (desc->id == AXP20X_DCDC2) {
> > @@ -436,11 +438,13 @@ static int axp20x_set_ramp_delay(struct regulator_dev *rdev, int ramp)
> >  static int axp20x_regulator_enable_regmap(struct regulator_dev *rdev)
> >  {
> >  	struct axp20x_dev *axp20x = rdev_get_drvdata(rdev);
> > -	const struct regulator_desc *desc = rdev->desc;
> > +	const struct regulator_desc *desc;
> >  
> >  	if (!rdev)
> >  		return -EINVAL;
> >  
> > +	desc = rdev->desc;

Called from _regulator_do_enable() and rdev can't be NULL:

	ret = rdev->desc->ops->enable(rdev);

regards,
dan carpenter