Commit 8a4c5c32 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki Committed by Bjorn Helgaas

PCI: Check parent kobject in pci_destroy_dev()

If pci_stop_and_remove_bus_device() is run concurrently for a device and
its parent bridge via remove_callback(), both code paths attempt to acquire
pci_rescan_remove_lock.  If the child device removal acquires it first,
there will be no problems.  However, if the parent bridge removal acquires
it first, it will eventually execute pci_destroy_dev() for the child
device, but that device object will not be freed yet due to the reference
held by the concurrent child removal.  Consequently, both
pci_stop_bus_device() and pci_remove_bus_device() will be executed for that
device unnecessarily and pci_destroy_dev() will see a corrupted list head
in that object.  Moreover, an excess put_device() will be executed for that
device in that case which may lead to a use-after-free in the final
kobject_put() done by sysfs_schedule_callback_work().

To avoid that problem, make pci_destroy_dev() check if the device's parent
kobject is NULL, which only happens after device_del() has already run for
it.  Make pci_destroy_dev() return immediately whithout doing anything in
that case.
Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: default avatarBjorn Helgaas <bhelgaas@google.com>
parent a83919e0
......@@ -20,6 +20,9 @@ static void pci_stop_dev(struct pci_dev *dev)
static void pci_destroy_dev(struct pci_dev *dev)
{
if (!dev->dev.kobj.parent)
return;
device_del(&dev->dev);
put_device(&dev->dev);
......
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