linux-kernel - Re: [PATCH] gpio: tpmx86: fix uninitialized variable girq

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Date:   Wed, 14 Sep 2022 08:35:22 +0100
From:   Marc Zyngier <maz@...nel.org>
To:     Dongliang Mu <dzm91@...t.edu.cn>
Cc:     Linus Walleij <linus.walleij@...aro.org>,
        Bartosz Golaszewski <brgl@...ev.pl>,
        Dongliang Mu <mudongliangabcd@...il.com>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] gpio: tpmx86: fix uninitialized variable girq

On Wed, 14 Sep 2022 06:18:42 +0100,
Dongliang Mu <dzm91@...t.edu.cn> wrote:
> 
> From: Dongliang Mu <mudongliangabcd@...il.com>
> 
> The commit 924610607f19 ("gpio: tpmx86: Move PM device over to
> irq domain") adds a dereference of girq that may be uninitialized.
> 
> Fix this by initializing girq and checking irq before invoking
> irq_domain_set_pm_device.
> 
> Fixes: 924610607f19 ("gpio: tpmx86: Move PM device over to irq domain")
> Signed-off-by: Dongliang Mu <mudongliangabcd@...il.com>
> ---
>  drivers/gpio/gpio-tqmx86.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpio/gpio-tqmx86.c b/drivers/gpio/gpio-tqmx86.c
> index fa4bc7481f9a..bdef182c11c2 100644
> --- a/drivers/gpio/gpio-tqmx86.c
> +++ b/drivers/gpio/gpio-tqmx86.c
> @@ -231,7 +231,7 @@ static int tqmx86_gpio_probe(struct platform_device *pdev)
>  	struct device *dev = &pdev->dev;
>  	struct tqmx86_gpio_data *gpio;
>  	struct gpio_chip *chip;
> -	struct gpio_irq_chip *girq;
> +	struct gpio_irq_chip *girq = NULL;
>  	void __iomem *io_base;
>  	struct resource *res;
>  	int ret, irq;
> @@ -315,7 +315,9 @@ static int tqmx86_gpio_probe(struct platform_device *pdev)
>  		goto out_pm_dis;
>  	}
>  
> -	irq_domain_set_pm_device(girq->domain, dev);
> +	if (girq) {
> +		irq_domain_set_pm_device(girq->domain, dev);
> +	}
>  
>  	dev_info(dev, "GPIO functionality initialized with %d pins\n",
>  		 chip->ngpio);

I wonder if a better fix wouldn't be to directly hoist the
irq_domain_set_pm_device() call into the 'if (irq > 0)' block.

Thanks,

	M.

-- 
Without deviation from the norm, progress is not possible.