linux-kernel - Re: [PATCH] pinctrl: madera: Fix uninitialized variable issue in madera_mux_set

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Date:   Wed, 10 Oct 2018 15:33:40 +0100
From:   Charles Keepax <ckeepax@...nsource.cirrus.com>
To:     "Gustavo A. R. Silva" <gustavo@...eddedor.com>
CC:     Richard Fitzgerald <rf@...nsource.cirrus.com>,
        Linus Walleij <linus.walleij@...aro.org>,
        <alsa-devel@...a-project.org>, <patches@...nsource.cirrus.com>,
        <linux-gpio@...r.kernel.org>, <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] pinctrl: madera: Fix uninitialized variable issue in
 madera_mux_set_mux

On Wed, Oct 10, 2018 at 04:13:53PM +0200, Gustavo A. R. Silva wrote:
> There is a potential execution path in which variable *ret* is checked
> in an IF statement, and then its value is used to report an error at
> line 659 without being properly initialized previously:
> 
> 659 if (ret)
> 660	dev_err(priv->dev, "Failed to write to 0x%x (%d)\n", reg, ret);
> 
> Fix this by initializing variable *ret* to -1.
> 
> Addresses-Coverity-ID: 1471969 ("Uninitialized scalar variable")
> Fixes: 218d72a77b0b ("pinctrl: madera: Add driver for Cirrus Logic Madera codecs")
> Signed-off-by: Gustavo A. R. Silva <gustavo@...eddedor.com>
> ---
>  drivers/pinctrl/cirrus/pinctrl-madera-core.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/pinctrl/cirrus/pinctrl-madera-core.c b/drivers/pinctrl/cirrus/pinctrl-madera-core.c
> index 0266302..a99ace8 100644
> --- a/drivers/pinctrl/cirrus/pinctrl-madera-core.c
> +++ b/drivers/pinctrl/cirrus/pinctrl-madera-core.c
> @@ -608,7 +608,7 @@ static int madera_mux_set_mux(struct pinctrl_dev *pctldev,
>  	unsigned int n_chip_groups = priv->chip->n_pin_groups;
>  	const char *func_name = madera_mux_funcs[selector].name;
>  	unsigned int reg;
> -	int i, ret;
> +	int i, ret = -1;
>  

I don't believe this would fully address the issue since if you
initialise ret to -1 you will still drop into the if statement
and you will use the reg variable which should also be
uninitialised on that code path.

Feels like initialising to 0 would probably be better anyway
since the code path looks like the case were you have n_pins == 0
and nothing really failed in that case just nothing needed to be
done.

Thanks,
Charles

>  	dev_dbg(priv->dev, "%s selecting %u (%s) for group %u (%s)\n",
>  		__func__, selector, func_name, group,
> -- 
> 2.7.4