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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>
This commit is contained in:
Oliver Neukum 2008-03-31 16:27:30 +02:00 committed by Jiri Kosina
parent abdff0f774
commit 69626f23bc
2 changed files with 4 additions and 1 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
drivers/hid/usbhid/hid-core.c
View File

@ -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);

1
include/linux/hid.h
View File

@ -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;