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Commit 69626f23 authored by Oliver Neukum's avatar Oliver Neukum Committed by Jiri Kosina
Browse files

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: default avatarOliver Neukum <oneukum@suse.de>
Signed-off-by: default avatarJiri Kosina <jkosina@suse.cz>
parent abdff0f7

drivers/hid/usbhid/hid-core.c

+3 −1
Original line number Diff line number Diff line
@@ -82,6 +82,7 @@ static int hid_start_in(struct hid_device *hid) 


	spin_lock_irqsave(&usbhid->inlock, flags);

	if (hid->open > 0 && !test_bit(HID_SUSPENDED, &usbhid->iofl) &&

			!test_bit(HID_DISCONNECTED, &usbhid->iofl) &&

			!test_and_set_bit(HID_IN_RUNNING, &usbhid->iofl)) {

		rc = usb_submit_urb(usbhid->urbin, GFP_ATOMIC);

		if (rc != 0)
@@ -155,7 +156,7 @@ static void hid_io_error(struct hid_device *hid) 
	spin_lock_irqsave(&usbhid->inlock, flags);



	/* Stop when disconnected */

	if (usb_get_intfdata(usbhid->intf) == NULL)

	if (test_bit(HID_DISCONNECTED, &usbhid->iofl))

		goto done;



	/* If it has been a while since the last error, we'll assume
@@ -941,6 +942,7 @@ static void hid_disconnect(struct usb_interface *intf) 


	spin_lock_irq(&usbhid->inlock);	/* Sync with error handler */

	usb_set_intfdata(intf, NULL);

	set_bit(HID_DISCONNECTED, &usbhid->iofl);

	spin_unlock_irq(&usbhid->inlock);

	usb_kill_urb(usbhid->urbin);

	usb_kill_urb(usbhid->urbout);

include/linux/hid.h

+1 −0
Original line number Diff line number Diff line
@@ -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;