linux-kernel - [PATCH 1/2] gpio: mt7621: report failure of devm

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Date:   Wed, 21 Nov 2018 19:06:12 +0100
From:   Nicholas Mc Guire <hofrat@...dl.org>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     Bartosz Golaszewski <bgolaszewski@...libre.com>,
        Matthias Brugger <matthias.bgg@...il.com>,
        Sergio Paracuellos <sergio.paracuellos@...il.com>,
        linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org,
        Nicholas Mc Guire <hofrat@...dl.org>
Subject: [PATCH 1/2] gpio: mt7621: report failure of devm_kasprintf()

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")
---

V2: The dev_err() for the unlikely case of the devm_kasprintf()
    failing was removed on request from Bartosz Golaszewski 
    <bgolaszewski@...libre.com>

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 | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/drivers/gpio/gpio-mt7621.c b/drivers/gpio/gpio-mt7621.c
index d72af6f..1ec95bc 100644
--- a/drivers/gpio/gpio-mt7621.c
+++ b/drivers/gpio/gpio-mt7621.c
@@ -244,6 +244,8 @@ 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)
+		return -ENOMEM;
 
 	ret = devm_gpiochip_add_data(dev, &rg->chip, mtk);
 	if (ret < 0) {
-- 
2.1.4