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| author | Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> | 2013-12-03 10:59:58 -0500 |
|---|---|---|
| committer | Rafael J. Wysocki <rafael.j.wysocki@intel.com> | 2013-12-03 22:05:22 +0100 |
| commit | 813e8e3d6aaa0b511126cce15c16a931afffe768 (patch) | |
| tree | b05dcb3ca915ff80b4f1b2b15bc1e28b04de8cb1 /drivers/cpuidle/cpuidle.c | |
| parent | 22e580d07f6529a395c129575127ea6d860aed3a (diff) | |
| download | lwn-813e8e3d6aaa0b511126cce15c16a931afffe768.tar.gz lwn-813e8e3d6aaa0b511126cce15c16a931afffe768.zip | |
cpuidle: Check for dev before deregistering it.
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>
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/cpuidle/cpuidle.c')
| -rw-r--r-- | drivers/cpuidle/cpuidle.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index 2a991e468f78..a55e68f2cfc8 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -400,7 +400,7 @@ EXPORT_SYMBOL_GPL(cpuidle_register_device); */ void cpuidle_unregister_device(struct cpuidle_device *dev) { - if (dev->registered == 0) + if (!dev || dev->registered == 0) return; cpuidle_pause_and_lock(); |