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From:   Bartosz Golaszewski <bgolaszewski@baylibre.com>
Date:   Wed, 21 Nov 2018 17:43:43 +0100
Message-ID: <CAMpxmJUNYWqk4PEKcZ5o5PMR3RhMhudK+Pf+Pfo64mvJ8ND2wQ@mail.gmail.com>
Subject: Re: [PATCH] gpio: mt7621: handle failure of devm_kasprintf()
To:     hofrat@osadl.org
Cc:     Linus Walleij <linus.walleij@linaro.org>, matthias.bgg@gmail.com,
        sergio.paracuellos@gmail.com,
        linux-gpio <linux-gpio@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        arm-soc <linux-arm-kernel@lists.infradead.org>,
        linux-mediatek@lists.infradead.org
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=C5=9Br., 21 lis 2018 o 17:39 Nicholas Mc Guire <hofrat@osadl.org> napisa=
=C5=82(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@osadl.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=3Dy,
> GPIOLIB=3Dy, GPIO_MT7621=3Dy
>
> 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 =3D mediatek_gpio_xlate;
>         rg->chip.label =3D 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 =3D devm_gpiochip_add_data(dev, &rg->chip, mtk);
>         if (ret < 0) {
> --
> 2.1.4
>