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usb: hub: take hub->hdev reference when processing from eventlist 

commit c605f3cdff53a743f6d875b76956b239deca1272 upstream.

During surprise device hotplug removal tests, it was observed that
hub_events may try to call usb_lock_device on a device that has already
been freed. Protect the usb_device by taking out a reference (under the
hub_event_lock) when hub_events pulls it off the list, returning the
reference after hub_events is finished using it.

Signed-off-by: Joe Lawrence <joe.lawrence@stratus.com>
Suggested-by: David Bulkow <david.bulkow@stratus.com> for using kref
Suggested-by: Alan Stern <stern@rowland.harvard.edu> for placement
Acked-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Joe Lawrence 2014-09-10 15:07:50 -04:00 committed by Greg Kroah-Hartman
parent 1fdbb939b8
commit 14200eade5
1 changed files with 3 additions and 1 deletions
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4
drivers/usb/core/hub.c
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@ -4702,9 +4702,10 @@ static void hub_events(void)
hub = list_entry(tmp, struct usb_hub, event_list);
kref_get(&hub->kref);
hdev = hub->hdev;
usb_get_dev(hdev);
spin_unlock_irq(&hub_event_lock);
hdev = hub->hdev;
hub_dev = hub->intfdev;
intf = to_usb_interface(hub_dev);
dev_dbg(hub_dev, "state %d ports %d chg %04x evt %04x\n",
@ -4919,6 +4920,7 @@ static void hub_events(void)
usb_autopm_put_interface(intf);
loop_disconnected:
usb_unlock_device(hdev);
usb_put_dev(hdev);
kref_put(&hub->kref, hub_release);
} /* end while (1) */