[PATCH 5.2 24/85] gpio: fix line flag validation in linehandle_create

Greg Kroah-Hartman
2019-09-18T06:25:03Z

From: Kent Gibson <warthog618@gmail.com>

commit e95fbc130a162ba9ad956311b95aa0da269eea48 upstream.

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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
drivers/gpio/gpiolib.c | 8 ++++++++
1 file changed, 8 insertions(+)

--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -536,6 +536,14 @@ static int linehandle_create(struct gpio
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
* electrical result would be disastrous.