linux-kernel - [PATCH] gpiolib: sanitize flags before allocating memory in lineevent

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Date:   Mon, 16 Sep 2019 11:46:23 +0200
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Linus Walleij <linus.walleij@...aro.org>
Cc:     linux-gpio@...r.kernel.org, linux-kernel@...r.kernel.org,
        Bartosz Golaszewski <bgolaszewski@...libre.com>
Subject: [PATCH] gpiolib: sanitize flags before allocating memory in lineevent_create()

From: Bartosz Golaszewski <bgolaszewski@...libre.com>

Move all the flags sanitization before any memory allocation in
lineevent_create() in order to remove a couple unneeded gotos.

Signed-off-by: Bartosz Golaszewski <bgolaszewski@...libre.com>
---
 drivers/gpio/gpiolib.c | 42 ++++++++++++++++++------------------------
 1 file changed, 18 insertions(+), 24 deletions(-)

diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c
index d9074191edef..194b0bcdcfb7 100644
--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -899,6 +899,24 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
 
 	if (copy_from_user(&eventreq, ip, sizeof(eventreq)))
 		return -EFAULT;
+	
+	offset = eventreq.lineoffset;
+	lflags = eventreq.handleflags;
+	eflags = eventreq.eventflags;
+
+	if (offset >= gdev->ngpio)
+		return -EINVAL;
+
+	/* Return an error if a unknown flag is set */
+	if ((lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS) ||
+	    (eflags & ~GPIOEVENT_REQUEST_VALID_FLAGS))
+		return -EINVAL;
+
+	/* This is just wrong: we don't look for events on output lines */
+	if ((lflags & GPIOHANDLE_REQUEST_OUTPUT) ||
+	    (lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN) ||
+	    (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE))
+		return -EINVAL;
 
 	le = kzalloc(sizeof(*le), GFP_KERNEL);
 	if (!le)
@@ -917,30 +935,6 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
 		}
 	}
 
-	offset = eventreq.lineoffset;
-	lflags = eventreq.handleflags;
-	eflags = eventreq.eventflags;
-
-	if (offset >= gdev->ngpio) {
-		ret = -EINVAL;
-		goto out_free_label;
-	}
-
-	/* Return an error if a unknown flag is set */
-	if ((lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS) ||
-	    (eflags & ~GPIOEVENT_REQUEST_VALID_FLAGS)) {
-		ret = -EINVAL;
-		goto out_free_label;
-	}
-
-	/* This is just wrong: we don't look for events on output lines */
-	if ((lflags & GPIOHANDLE_REQUEST_OUTPUT) ||
-	    (lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN) ||
-	    (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE)) {
-		ret = -EINVAL;
-		goto out_free_label;
-	}
-
 	desc = &gdev->descs[offset];
 	ret = gpiod_request(desc, le->label);
 	if (ret)
-- 
2.21.0