staging: cs5535_gpio: check put_user() return code

put_user() may fail, if so return -EFAULT.
Signed-off-by: Vasiliy Kulikov <segoon@openwall.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/cs5535_gpio/cs5535_gpio.c

@@ -146,7 +146,8 @@ static ssize_t cs5535_gpio_read(struct file *file, char __user *buf,
 
 	/* add a line-feed if there is room */
 	if ((i == ARRAY_SIZE(rm)) && (count < len)) {
-		put_user('\n', buf + count);
+		if (put_user('\n', buf + count))
+			return -EFAULT;
 		count++;
 	}