gpio: fix line flag validation in linehandle_create

linehandle_create should not allow both GPIOHANDLE_REQUEST_INPUT
and GPIOHANDLE_REQUEST_OUTPUT to be set.

Fixes: d7c51b47ac11 ("gpio: userspace ABI for reading/writing GPIO lines")
Cc: stable <stable@vger.kernel.org>
Signed-off-by: Kent Gibson <warthog618@gmail.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index cca7490..7502230 100644 (file)
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -535,6 +535,14 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
        if (lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS)
                return -EINVAL;
 
+       /*
+        * Do not allow both INPUT & OUTPUT flags to be set as they are
+        * contradictory.
+        */
+       if ((lflags & GPIOHANDLE_REQUEST_INPUT) &&
+           (lflags & GPIOHANDLE_REQUEST_OUTPUT))
+               return -EINVAL;
+
        /*
         * Do not allow OPEN_SOURCE & OPEN_DRAIN flags in a single request. If
         * the hardware actually supports enabling both at the same time the