Re: [PATCH v9 7/9] pinctrl: mediatek: mt6397: Add MediaTek MT6392

[sashiko-bot@kernel.org]

Thank you for your contribution! Sashiko AI review found 1 potential issue(s) to consider:

Pre-existing issues:
- [High] Unbinding the pinctrl driver leads to a Use-After-Free of the gpiochip structure because it is never unregistered.
--

--- Patch [7]: [PATCH v9 7/9] pinctrl: mediatek: mt6397: Add MediaTek MT6392 ---
commit 8de420548b885f3f527c1ef77d05dce6a4500878
Author: Luca Leonardo Scorcia <l.scorcia@gmail.com>

pinctrl: mediatek: mt6397: Add MediaTek MT6392
    
This commit adds support for the MT6392 pinctrl device by introducing its pins
definition and updating the MT6397 driver to retrieve device data from the
match table.

> diff --git a/drivers/pinctrl/mediatek/pinctrl-mt6397.c b/drivers/pinctrl/mediatek/pinctrl-mt6397.c
> index 03d0f65d7bcc1..8ba02e70595ce 100644
> --- a/drivers/pinctrl/mediatek/pinctrl-mt6397.c
> +++ b/drivers/pinctrl/mediatek/pinctrl-mt6397.c

[ ... ]

> @@ -40,13 +62,24 @@ static const struct mtk_pinctrl_devdata mt6397_pinctrl_data = {
>  static int mt6397_pinctrl_probe(struct platform_device *pdev)
>  {
>  	struct mt6397_chip *mt6397;
> +	const struct mtk_pinctrl_devdata *data;
> +
> +	data = device_get_match_data(&pdev->dev);
> +	if (!data)
> +		return -ENOENT;
>  
>  	mt6397 = dev_get_drvdata(pdev->dev.parent);
> -	return mtk_pctrl_init(pdev, &mt6397_pinctrl_data, mt6397->regmap);
> +	return mtk_pctrl_init(pdev, data, mt6397->regmap);
>  }

[Severity: High]
This is a pre-existing issue, but does unbinding this driver lead to a
use-after-free of the gpiochip structure?

Looking at mtk_pctrl_init() in drivers/pinctrl/mediatek/pinctrl-mtk-common.c,
the pctl->chip memory is allocated using devm_kzalloc() but registered using
the unmanaged gpiochip_add_data() function:

drivers/pinctrl/mediatek/pinctrl-mtk-common.c:mtk_pctrl_init() {
    ...
    pctl->chip = devm_kzalloc(&pdev->dev, sizeof(*pctl->chip), GFP_KERNEL);
    ...
    ret = gpiochip_add_data(pctl->chip, pctl);
    ...
}

Since the MT6397 platform driver lacks a .remove callback to explicitly call
gpiochip_remove(), unbinding the driver via sysfs causes devres to free
pctl->chip while it remains registered in the global gpiolib lists.

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20260820122242.120039-1-l.scorcia@gmail.com?part=7