From: Oliver Neukum <oliver@neukum.org>
Date: Mon, 31 Mar 2008 14:27:30 +0000 (+0200)
Subject: HID: fix race between open() and disconnect() in usbhid
X-Git-Tag: v2.6.26-rc1~1107^2~6
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=69626f23bce6521367ac1e6a2a6e8fba8f0a848a;p=pandora-kernel.git

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>
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