[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
Cc: Bartosz Golaszewski <redacted>
Cc: Arnd Bergmann <arnd@arndb.de>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <redacted>
---
 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);
 

-- 
2.14.3

2018-01-22 13:21 GMT+01:00 Linus Walleij [off-list ref]:

Reviewed-by: Bartosz Golaszewski <redacted>

On Mon, Jan 22, 2018 at 1:21 PM, Linus Walleij [off-list ref] wrote:

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
Cc: Bartosz Golaszewski <redacted>
Cc: Arnd Bergmann <arnd@arndb.de>
Reported-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Linus Walleij <redacted>
---
 drivers/gpio/gpiolib.c | 3 +++
 1 file changed, 3 insertions(+)

Reviewed-by: Arnd Bergmann <arnd@arndb.de>