[PATCH 4.9 040/172] gpiolib: fix filtering out unwanted events

[Greg Kroah-Hartman]

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

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

From: Bartosz Golaszewski <brgl@xxxxxxxx>

commit ad537b822577fcc143325786cd6ad50d7b9df31c upstream.

GPIOEVENT_REQUEST_BOTH_EDGES is not a single flag, but a binary OR of
GPIOEVENT_REQUEST_RISING_EDGE and GPIOEVENT_REQUEST_FALLING_EDGE.

The expression 'le->eflags & GPIOEVENT_REQUEST_BOTH_EDGES' we'll get
evaluated to true even if only one event type was requested.

Fix it by checking both RISING & FALLING flags explicitly.

Fixes: 61f922db7221 ("gpio: userspace ABI for reading GPIO line events")
Signed-off-by: Bartosz Golaszewski <brgl@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, 2 insertions(+), 1 deletion(-)

--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -707,7 +707,8 @@ static irqreturn_t lineevent_irq_thread(
 
 	ge.timestamp = ktime_get_real_ns();
 
-	if (le->eflags & GPIOEVENT_REQUEST_BOTH_EDGES) {
+	if (le->eflags & GPIOEVENT_REQUEST_RISING_EDGE
+	    && le->eflags & GPIOEVENT_REQUEST_FALLING_EDGE) {
 		int level = gpiod_get_value_cansleep(le->desc);
 
 		if (level)