lkml.org 
[lkml]   [2014]   [Jan]   [2]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 3.8 89/91] cpuidle: Check for dev before deregistering it.
Date
3.8.13.15 -stable review patch.  If anyone has any objections, please let me know.

------------------

From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

commit 813e8e3d6aaa0b511126cce15c16a931afffe768 upstream.

If not, we could end up in the unfortunate situation where
we dereference a NULL pointer b/c we have cpuidle disabled.

This is the case when booting under Xen (which uses the
ACPI P/C states but disables the CPU idle driver) - and can
be easily reproduced when booting with cpuidle.off=1.

BUG: unable to handle kernel NULL pointer dereference at (null)
IP: [<ffffffff8156db4a>] cpuidle_unregister_device+0x2a/0x90
.. snip..
Call Trace:
[<ffffffff813b15b4>] acpi_processor_power_exit+0x3c/0x5c
[<ffffffff813af0a9>] acpi_processor_stop+0x61/0xb6
[<ffffffff814215bf>] __device_release_driver+0fffff81421653>] device_release_driver+0x23/0x30
[<ffffffff81420ed8>] bus_remove_device+0x108/0x180
[<ffffffff8141d9d9>] device_del+0x129/0x1c0
[<ffffffff813cb4b0>] ? unregister_xenbus_watch+0x1f0/0x1f0
[<ffffffff8141da8e>] device_unregister+0x1e/0x60
[<ffffffff814243e9>] unregister_cpu+0x39/0x60
[<ffffffff81019e03>] arch_unregister_cpu+0x23/0x30
[<ffffffff813c3c51>] handle_vcpu_hotplug_event+0xc1/0xe0
[<ffffffff813cb4f5>] xenwatch_thread+0x45/0x120
[<ffffffff810af010>] ? abort_exclusive_wait+0xb0/0xb0
[<ffffffff8108ec42>] kthread+0xd2/0xf0
[<ffffffff8108eb70>] ? kthread_create_on_node+0x180/0x180
[<ffffffff816ce17c>] ret_from_fork+0x7c/0xb0
[<ffffffff8108eb70>] ? kthread_create_on_node+0x180/0x180

This problem also appears in 3.12 and could be a candidate for backport.

Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
[ kamal: backport to 3.8 ]
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
---
drivers/cpuidle/cpuidle.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
index e1f6860..7decd90 100644
--- a/drivers/cpuidle/cpuidle.c
+++ b/drivers/cpuidle/cpuidle.c
@@ -460,11 +460,13 @@ EXPORT_SYMBOL_GPL(cpuidle_register_device);
*/
void cpuidle_unregister_device(struct cpuidle_device *dev)
{
- struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev);
+ struct cpuidle_driver *drv;

- if (dev->registered == 0)
+ if (!dev || dev->registered == 0)
return;

+ drv = cpuidle_get_cpu_driver(dev);
+
cpuidle_pause_and_lock();

cpuidle_disable_device(dev);
--
1.8.3.2


\
 
 \ /
  Last update: 2014-01-02 19:01    [W:0.388 / U:0.160 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site