Commit e5332d54 authored Jul 16, 2018 by Bartosz Golaszewski Committed by Linus Walleij Jul 16, 2018

gpiolib: don't allow userspace to set values of input lines



User space can currently both read and set values of input lines using
the character device. This was not allowed by the old sysfs interface
nor is it a correct behavior.

Check the first descriptor in the set for the OUT flag when asked to
set values and return -EPERM if the line is input.

Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>

parent ad817297

drivers/gpio/gpiolib.c

+7 −1

Original line number	Diff line number	Diff line
		@@ -449,7 +449,13 @@ static long linehandle_ioctl(struct file *filep, unsigned int cmd,

		return 0;
		} else if (cmd == GPIOHANDLE_SET_LINE_VALUES_IOCTL) {
		/* TODO: check if descriptors are really output */
		/*
		* All line descriptors were created at once with the same
		* flags so just check if the first one is really output.
		*/
		if (!test_bit(FLAG_IS_OUT, &lh->descs[0]->flags))
		return -EPERM;

		if (copy_from_user(&ghd, ip, sizeof(ghd)))
		return -EFAULT;