linux-kernel - Re: [PATCH] gpio: mt7621: handle failure of devm

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Date:   Wed, 21 Nov 2018 17:43:43 +0100
From:   Bartosz Golaszewski <bgolaszewski@...libre.com>
To:     hofrat@...dl.org
Cc:     Linus Walleij <linus.walleij@...aro.org>, matthias.bgg@...il.com,
        sergio.paracuellos@...il.com,
        linux-gpio <linux-gpio@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>,
        arm-soc <linux-arm-kernel@...ts.infradead.org>,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH] gpio: mt7621: handle failure of devm_kasprintf()

śr., 21 lis 2018 o 17:39 Nicholas Mc Guire <hofrat@...dl.org> napisał(a):
>
> kasprintf() may return NULL on failure of internal allocation thus the
> assigned  label  is not safe if not explicitly checked. On error
> mediatek_gpio_bank_probe() returns negative values so -ENOMEM in the
> (unlikely) failure case should be fine here.
>
> Signed-off-by: Nicholas Mc Guire <hofrat@...dl.org>
> Fixes: 4ba9c3afda41 ("gpio: mt7621: Add a driver for MT7621")
> ---
>
> Problem located with experimental coccinelle script
>
> Patch was compile tested with: omega2p_defconfig, SOC_MT7621=y,
> GPIOLIB=y, GPIO_MT7621=y
>
> Patch is against 4.20-rc3 (localversion-next is next-20181121)
>
>  drivers/gpio/gpio-mt7621.c | 4 ++++
>  1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpio/gpio-mt7621.c b/drivers/gpio/gpio-mt7621.c
> index d72af6f..42f0c67 100644
> --- a/drivers/gpio/gpio-mt7621.c
> +++ b/drivers/gpio/gpio-mt7621.c
> @@ -244,6 +244,10 @@ mediatek_gpio_bank_probe(struct device *dev,
>         rg->chip.of_xlate = mediatek_gpio_xlate;
>         rg->chip.label = devm_kasprintf(dev, GFP_KERNEL, "%s-bank%d",
>                                         dev_name(dev), bank);
> +       if (!rg->chip.label) {
> +               dev_err(dev, "Could not allocate label\n");

No need for an error message here, an -ENOMEM says enough.

Bart

> +               return -ENOMEM;
> +       }
>
>         ret = devm_gpiochip_add_data(dev, &rg->chip, mtk);
>         if (ret < 0) {
> --
> 2.1.4
>