From 418ee8e91fe7fc90ffb6bce391304e084f77bce4 Mon Sep 17 00:00:00 2001
From: Bartosz Golaszewski <brgl@bgdev.pl>
Date: Mon, 16 Oct 2017 11:32:29 +0200
Subject: [PATCH] gpiolib: only check line handle flags once
Git-commit: 418ee8e91fe7fc90ffb6bce391304e084f77bce4
Patch-mainline: v4.15-rc1
References: bsc#1051510

There's no need to check the validity of handle request flags more
than once, right after copying the data from user. Move the check
out of the for loop and simplify the error path by bailing out before
allocating any resources.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Takashi Iwai <tiwai@suse.de>

---
 drivers/gpio/gpiolib.c |   14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

--- a/drivers/gpio/gpiolib.c
+++ b/drivers/gpio/gpiolib.c
@@ -427,12 +427,19 @@ static int linehandle_create(struct gpio
 	struct linehandle_state *lh;
 	struct file *file;
 	int fd, i, ret;
+	u32 lflags;
 
 	if (copy_from_user(&handlereq, ip, sizeof(handlereq)))
 		return -EFAULT;
 	if ((handlereq.lines == 0) || (handlereq.lines > GPIOHANDLES_MAX))
 		return -EINVAL;
 
+	lflags = handlereq.flags;
+
+	/* Return an error if an unknown flag is set */
+	if (lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS)
+		return -EINVAL;
+
 	lh = kzalloc(sizeof(*lh), GFP_KERNEL);
 	if (!lh)
 		return -ENOMEM;
@@ -453,19 +460,12 @@ static int linehandle_create(struct gpio
 	/* Request each GPIO */
 	for (i = 0; i < handlereq.lines; i++) {
 		u32 offset = handlereq.lineoffsets[i];
-		u32 lflags = handlereq.flags;
 		struct gpio_desc *desc;
 
 		if (offset >= gdev->ngpio) {
 			ret = -EINVAL;
 			goto out_free_descs;
 		}
-
-		/* Return an error if a unknown flag is set */
-		if (lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS) {
-			ret = -EINVAL;
-			goto out_free_descs;
-		}
 
 		desc = &gdev->descs[offset];
 		ret = gpiod_request(desc, lh->label);