HID: fix race between open() and disconnect() in usbhid

There is a window:

task A					task B
spin_lock_irq(&usbhid->inlock);	/* Sync with error handler */
usb_set_intfdata(intf, NULL);
spin_unlock_irq(&usbhid->inlock);
usb_kill_urb(usbhid->urbin);
usb_kill_urb(usbhid->urbout);
usb_kill_urb(usbhid->urbctrl);

del_timer_sync(&usbhid->io_retry);
cancel_work_sync(&usbhid->reset_work);

						if (!hid->open++) {
							res = usb_autopm_get_interface(usbhid->intf);
							if (res < 0) {
								hid->open--;
								return -EIO;
							}
						}
						if (hid_start_in(hid))

if (hid->claimed & HID_CLAIMED_INPUT)
	hidinput_disconnect(hid);

in which an open() to an already disconnected device will submit an URB
to an undead device. In case disconnect() was called by an ioctl, this'll
oops. Fix by introducing a new flag and checking it in hid_start_in().

Signed-off-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/hid.h b/include/linux/hid.h
index fe4ac31eced2..d951ec411241 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -424,6 +424,7 @@ struct hid_control_fifo {
 #define HID_RESET_PENDING       4
 #define HID_SUSPENDED           5
 #define HID_CLEAR_HALT          6
+#define HID_DISCONNECTED        7
 
 struct hid_input {
         struct list_head list;