From 24bd3efc9d1efb5f756a7c6f807a36ddb6adc671 Mon Sep 17 00:00:00 2001
From: Linus Walleij <linus.walleij@linaro.org>
Date: Mon, 22 Jan 2018 13:19:28 +0100
Subject: [PATCH] gpio: Fix kernel stack leak to userspace

The GPIO event descriptor was leaking kernel stack to
userspace because we don't zero the variable before
use. Ooops. Fix this.

Cc: stable@vger.kernel.org
Reported-by: Arnd Bergmann <arnd@arndb.de>
Reviewed-by: Bartosz Golaszewski <brgl@bgdev.pl>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
---
 drivers/gpio/gpiolib.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index 37e31ba82ca0..754836e4ca0e 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -744,6 +744,9 @@ static irqreturn_t lineevent_irq_thread(int irq, void *p)
 	struct gpioevent_data ge;
 	int ret, level;
 
+	/* Do not leak kernel stack to userspace */
+	memset(&ge, 0, sizeof(ge));
+
 	ge.timestamp = ktime_get_real_ns();
 	level = gpiod_get_value_cansleep(le->desc);