From: Adam Ford <aford173@gmail.com>
Subject: [PATCH V2 1/2] serial: mctrl_gpio: Check for NULL pointer
Date: Sun,  6 Oct 2019 11:33:11 -0500
Message-ID: <20191006163314.23191-1-aford173@gmail.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
Sender: linux-kernel-owner@vger.kernel.org
To: linux-serial@vger.kernel.org
Cc: Adam Ford <aford173@gmail.com>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Jiri Slaby <jslaby@suse.com>, Andy Shevchenko <andriy.shevchenko@linux.intel.com>, Vignesh R <vigneshr@ti.com>, Mika Westerberg <mika.westerberg@linux.intel.com>, Douglas Anderson <dianders@chromium.org>, Tony Lindgren <tony@atomide.com>, Yegor Yefremov <yegorslists@googlemail.com>, linux-kernel@vger.kernel.org
List-Id: linux-serial@vger.kernel.org

When using mctrl_gpio_to_gpiod, it dereferences gpios into a single
requested GPIO.  This dereferencing can break if gpios is NULL,
so this patch adds a NULL check before dereferencing it.  If
gpios is NULL, this function will also return NULL.

Signed-off-by: Adam Ford <aford173@gmail.com>
---
V2:  This patch is new to the V2 of this series, so patch 2/2 can 
     work without risking a NULL dereference
diff --git a/drivers/tty/serial/serial_mctrl_gpio.c b/drivers/tty/serial/serial_mctrl_gpio.c
index d9074303c88e..fb4781292d40 100644
--- a/drivers/tty/serial/serial_mctrl_gpio.c
+++ b/drivers/tty/serial/serial_mctrl_gpio.c
@@ -66,6 +66,9 @@ EXPORT_SYMBOL_GPL(mctrl_gpio_set);
 struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
 				      enum mctrl_gpio_idx gidx)
 {
+	if (gpios == NULL)
+		return NULL;
+
 	return gpios->gpio[gidx];
 }
 EXPORT_SYMBOL_GPL(mctrl_gpio_to_gpiod);
-- 
2.17.1