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>
Signed-off-by: Zefan Li <lizefan@huawei.com>
diff --git a/drivers/usb/core/hub.c b/drivers/usb/core/hub.c
index 81763af..eb67c7d 100644
--- a/drivers/usb/core/hub.c
+++ b/drivers/usb/core/hub.c
@@ -3908,9 +3908,10 @@
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",
@@ -4398,6 +4399,7 @@
usb_autopm_put_interface(intf);
loop_disconnected:
usb_unlock_device(hdev);
+ usb_put_dev(hdev);
kref_put(&hub->kref, hub_release);
} /* end while (1) */