linux-kernel - [PATCH 4.19 17/50] gpio: fix line flag validation in linehandle

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Message-Id: <20190918061224.818165049@linuxfoundation.org>
Date:   Wed, 18 Sep 2019 08:19:00 +0200
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Kent Gibson <warthog618@...il.com>,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: [PATCH 4.19 17/50] gpio: fix line flag validation in linehandle_create

From: Kent Gibson <warthog618@...il.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@...r.kernel.org>
Signed-off-by: Kent Gibson <warthog618@...il.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

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

--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -525,6 +525,14 @@ 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.