[PATCH 4.14 006/156] gpio: Fix kernel stack leak to userspace

From: Greg Kroah-Hartman
Date: Fri Feb 02 2018 - 12:45:09 EST


4.14-stable review patch. If anyone has any objections, please let me know.

------------------

From: Linus Walleij <linus.walleij@xxxxxxxxxx>

commit 24bd3efc9d1efb5f756a7c6f807a36ddb6adc671 upstream.

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

Reported-by: Arnd Bergmann <arnd@xxxxxxxx>
Reviewed-by: Bartosz Golaszewski <brgl@xxxxxxxx>
Reviewed-by: Arnd Bergmann <arnd@xxxxxxxx>
Signed-off-by: Linus Walleij <linus.walleij@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>

---
drivers/gpio/gpiolib.c | 3 +++
1 file changed, 3 insertions(+)

--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -723,6 +723,9 @@ static irqreturn_t lineevent_irq_thread(
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);