From: "Rafael J. Wysocki" <rjw@rjwysocki.net>
To: Yinghai Lu <yinghai@kernel.org>
Cc: Bjorn Helgaas <bhelgaas@google.com>,
"Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
Gu Zheng <guz.fnst@cn.fujitsu.com>,
Guo Chao <yan@linux.vnet.ibm.com>,
"linux-pci@vger.kernel.org" <linux-pci@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Mika Westerberg <mika.westerberg@linux.intel.com>,
Myron Stowe <myron.stowe@gmail.com>
Subject: [PATCH] PCI / remove: Check parent kobject in pci_destroy_dev() (was: Re: [PATCH v2 04/10] PCI: Destroy pci dev only once)
Date: Mon, 13 Jan 2014 02:03:16 +0100 [thread overview]
Message-ID: <3407940.L2vvqCPqy4@vostro.rjw.lan> (raw)
In-Reply-To: <1519414.GDlGZFCTSR@vostro.rjw.lan>
On Saturday, December 07, 2013 02:27:51 AM Rafael J. Wysocki wrote:
> On Thursday, December 05, 2013 10:52:36 PM Yinghai Lu wrote:
> > On Mon, Dec 2, 2013 at 6:49 AM, Rafael J. Wysocki <rjw@rjwysocki.net> wrote:
> > >
> > > Scenario 5: pci_stop_and_remove_bus_device() is run concurrently
> > > for a device and its parent bridge via remove_callback().
> > >
> > > In that case both code paths attempt to acquire
> > > pci_remove_rescan_mutex. 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 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().
> > >
> > > Index: linux-pm/include/linux/pci.h
> > > ===================================================================
> > > --- linux-pm.orig/include/linux/pci.h
> > > +++ linux-pm/include/linux/pci.h
> > > @@ -321,6 +321,7 @@ struct pci_dev {
> > > unsigned int multifunction:1;/* Part of multi-function device */
> > > /* keep track of device state */
> > > unsigned int is_added:1;
> > > + unsigned int is_gone:1;
> > > unsigned int is_busmaster:1; /* device is busmaster */
> > > unsigned int no_msi:1; /* device may not use msi */
> > > unsigned int block_cfg_access:1; /* config space access is blocked */
> > > Index: linux-pm/drivers/pci/remove.c
> > > ===================================================================
> > > --- linux-pm.orig/drivers/pci/remove.c
> > > +++ linux-pm/drivers/pci/remove.c
> > > @@ -34,6 +34,7 @@ static void pci_stop_dev(struct pci_dev
> > >
> > > static void pci_destroy_dev(struct pci_dev *dev)
> > > {
> > > + dev->is_gone = 1;
> > > device_del(&dev->dev);
> > >
> > > down_write(&pci_bus_sem);
> > > @@ -109,8 +110,10 @@ static void pci_remove_bus_device(struct
> > > */
> > > void pci_stop_and_remove_bus_device(struct pci_dev *dev)
> > > {
> > > - pci_stop_bus_device(dev);
> > > - pci_remove_bus_device(dev);
> > > + if (!dev->is_gone) {
> > > + pci_stop_bus_device(dev);
> > > + pci_remove_bus_device(dev);
> > > + }
> > > }
> > > EXPORT_SYMBOL(pci_stop_and_remove_bus_device);
> > >
> >
> > Yes, above change should address sys double remove problem.
>
> I've just realized that we don't need a new flag for that, though.
>
> It looks like we only need to check dev->dev.kobj.parent and return if that is
> NULL, because that means pci_destroy_dev() has run for that device already
> (I'm wondering why device_del() doesn't clear dev->parent, BTW, it looks like
> it should do that?).
>
> Of course, that still is going to be racy if we don't hold
> pci_remove_rescan_mutex around pci_stop_and_remove_bus_device() in every code
> path using it (or use another similar synchronization mechanism).
Before I forget about this, on top of the series I sent out on Friday.
Thanks,
Rafael
---
From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Subject: PCI / remove: 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: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/pci/remove.c | 3 +++
1 file changed, 3 insertions(+)
Index: linux-pm/drivers/pci/remove.c
===================================================================
--- linux-pm.orig/drivers/pci/remove.c
+++ linux-pm/drivers/pci/remove.c
@@ -34,6 +34,9 @@ static void pci_stop_dev(struct pci_dev
static void pci_destroy_dev(struct pci_dev *dev)
{
+ if (!dev->dev.kobj.parent)
+ return;
+
device_del(&dev->dev);
down_write(&pci_bus_sem);
next prev parent reply other threads:[~2014-01-13 0:49 UTC|newest]
Thread overview: 69+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-11-26 1:28 [PATCH v2 00/10] PCI: Double removing fix and allocate 64bit mmio pref Yinghai Lu
2013-11-26 1:28 ` [PATCH v2 01/10] PCI: Use device_release_driver in pci_stop_root_bus Yinghai Lu
2013-11-27 1:09 ` Rafael J. Wysocki
2013-11-26 1:28 ` [PATCH v2 02/10] PCI: Move back pci_proc_attach_devices calling Yinghai Lu
2013-11-26 1:28 ` [PATCH v2 03/10] PCI: Move resources and bus_list releasing to pci_release_dev Yinghai Lu
2013-11-27 1:15 ` Rafael J. Wysocki
2013-11-27 2:15 ` Yinghai Lu
2013-11-26 1:28 ` [PATCH v2 04/10] PCI: Destroy pci dev only once Yinghai Lu
2013-11-26 3:38 ` Bjorn Helgaas
2013-11-26 19:34 ` Yinghai Lu
2013-11-26 20:13 ` Yinghai Lu
2013-11-27 1:24 ` Rafael J. Wysocki
2013-11-27 2:26 ` Yinghai Lu
2013-11-29 23:38 ` Rafael J. Wysocki
2013-11-29 23:45 ` Rafael J. Wysocki
2013-11-30 0:31 ` Rafael J. Wysocki
2013-11-30 21:37 ` Rafael J. Wysocki
2013-11-30 22:27 ` Yinghai Lu
2013-12-01 1:24 ` Rafael J. Wysocki
2013-12-02 1:29 ` Rafael J. Wysocki
2013-12-02 14:49 ` Rafael J. Wysocki
2013-12-05 22:40 ` Bjorn Helgaas
2013-12-06 1:21 ` Rafael J. Wysocki
2013-12-06 6:29 ` Yinghai Lu
2014-01-10 14:20 ` [PATCH 0/9] PCI: Eliminate race conditions between hotplug and sysfs rescan/remove (Was: Re: [PATCH v2 04/10] PCI: Destroy pci dev only once) Rafael J. Wysocki
2014-01-10 14:22 ` [PATCH 1/9] PCI: Global rescan-remove lock Rafael J. Wysocki
2014-01-10 14:23 ` [PATCH 2/9] ACPI / PCI: Use global PCI rescan-remove locking in PCI root hotplug Rafael J. Wysocki
2014-01-10 14:24 ` [PATCH 3/9] ACPI / hotplug / PCI: Use global PCI rescan-remove locking Rafael J. Wysocki
2014-01-10 14:25 ` [PATCH 4/9] PCMCIA / cardbus: " Rafael J. Wysocki
2014-01-10 14:26 ` [PATCH 5/9] PCI / hotplug: " Rafael J. Wysocki
2014-01-10 14:27 ` [PATCH 6/9] platform / x86: " Rafael J. Wysocki
2014-01-10 14:27 ` [PATCH 7/9] MPT / PCI: Use pci_stop_and_remove_bus_device_locked() Rafael J. Wysocki
2014-01-10 14:28 ` [PATCH 8/9] powerpc / eeh_driver: Use global PCI rescan-remove locking Rafael J. Wysocki
2014-01-15 13:36 ` [Update][PATCH " Rafael J. Wysocki
2014-01-15 17:38 ` Bjorn Helgaas
2014-01-10 14:29 ` [PATCH 9/9] Xen / PCI: " Rafael J. Wysocki
2014-01-15 18:02 ` [PATCH 0/9] PCI: Eliminate race conditions between hotplug and sysfs rescan/remove (Was: Re: [PATCH v2 04/10] PCI: Destroy pci dev only once) Bjorn Helgaas
2013-12-06 6:52 ` [PATCH v2 04/10] PCI: Destroy pci dev only once Yinghai Lu
2013-12-07 1:27 ` Rafael J. Wysocki
2013-12-08 3:31 ` Yinghai Lu
2013-12-08 3:50 ` Greg Kroah-Hartman
2013-12-09 15:24 ` Ethan Zhao
2013-12-09 19:08 ` Greg Kroah-Hartman
2013-12-10 7:43 ` Ethan Zhao
2014-01-13 1:03 ` Rafael J. Wysocki [this message]
2013-11-27 1:17 ` Rafael J. Wysocki
2013-11-26 1:28 ` [PATCH v2 05/10] PCI: pcibus address to resource converting take bus directly Yinghai Lu
2013-11-26 1:28 ` [PATCH v2 06/10] PCI: Add pcibios_bus_addr_to_res() Yinghai Lu
2013-11-26 1:28 ` [PATCH v2 07/10] PCI: Try to allocate mem64 above 4G at first Yinghai Lu
2013-11-26 4:15 ` Bjorn Helgaas
2013-11-26 20:14 ` Yinghai Lu
2013-11-26 1:28 ` [PATCH v2 08/10] PCI: Try best to allocate pref mmio 64bit above 4g Yinghai Lu
2013-11-26 4:17 ` Bjorn Helgaas
2013-11-26 6:59 ` Guo Chao
2013-11-26 17:53 ` Bjorn Helgaas
2013-11-26 22:00 ` Yinghai Lu
2013-11-26 22:01 ` Bjorn Helgaas
2013-11-27 0:33 ` Yinghai Lu
2013-11-26 1:28 ` [PATCH v2 09/10] PCI: Sort pci root bus resources list Yinghai Lu
2013-11-26 4:18 ` Bjorn Helgaas
2013-11-26 1:28 ` [PATCH v2 10/10] intel-gtt: Read 64bit for gmar_bus_addr Yinghai Lu
2013-11-26 3:46 ` Bjorn Helgaas
2013-11-26 19:35 ` Yinghai Lu
2013-12-11 18:48 ` Bjorn Helgaas
2013-12-11 19:58 ` Yinghai Lu
2013-12-21 0:27 ` Bjorn Helgaas
2013-12-21 1:19 ` Yinghai Lu
2013-12-21 18:50 ` Bjorn Helgaas
2013-12-23 22:33 ` Bjorn Helgaas
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