Commit 439581ec authored Feb 25, 2011 by Peter Korsgaard Committed by Dmitry Torokhov Feb 27, 2011

Input: evdev - fix evdev_write return value on partial writes

As was recently brought up on the busybox list
(http://lists.busybox.net/pipermail/busybox/2011-January/074565.html

),
evdev_write doesn't properly check the count argument, which will
lead to a return value > count on partial writes if the remaining bytes
are accessible - causing userspace confusion.

Fix it by only handling each full input_event structure and return -EINVAL
if less than 1 struct was written, similar to how it is done in evdev_read.

Reported-by: Baruch Siach <baruch@tkos.co.il>
Signed-off-by: Peter Korsgaard <jacmet@sunsite.dk>
Acked-by: Henrik Rydberg <rydberg@euromail.se>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>

parent 50635115

drivers/input/evdev.c

+6 −4

Original line number	Diff line number	Diff line
		@@ -321,6 +321,9 @@ static ssize_t evdev_write(struct file file, const char __user buffer,
		struct input_event event;
		int retval;

		if (count < input_event_size())
		return -EINVAL;

		retval = mutex_lock_interruptible(&evdev->mutex);
		if (retval)
		return retval;
		@@ -330,17 +333,16 @@ static ssize_t evdev_write(struct file file, const char __user buffer,
		goto out;
		}

		while (retval < count) {

		do {
		if (input_event_from_user(buffer + retval, &event)) {
		retval = -EFAULT;
		goto out;
		}
		retval += input_event_size();

		input_inject_event(&evdev->handle,
		event.type, event.code, event.value);
		retval += input_event_size();
		}
		} while (retval + input_event_size() <= count);

		out:
		mutex_unlock(&evdev->mutex);