| Message ID | 1386772901-10584-1-git-send-email-luis.henriques@canonical.com |
|---|---|
| State | New |
| Headers | show |
diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c index fdc432f..68831be 100644 --- a/drivers/cpuidle/cpuidle.c +++ b/drivers/cpuidle/cpuidle.c @@ -434,7 +434,7 @@ void cpuidle_unregister_device(struct cpuidle_device *dev) { struct cpuidle_driver *drv = cpuidle_get_cpu_driver(dev); - if (dev->registered == 0) + if (!dev || dev->registered == 0) return; cpuidle_pause_and_lock();
This is a note to let you know that I have just added a patch titled cpuidle: Check for dev before deregistering it. to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree which can be found at: http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 3.11.y.z tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Luis ------ From b287829305c1dba7f173548eb5fc69aa78cf0d13 Mon Sep 17 00:00:00 2001 From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Date: Tue, 3 Dec 2013 10:59:58 -0500 Subject: cpuidle: Check for dev before deregistering it. 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> [ luis: backported to 3.11: adjusted context ] Signed-off-by: Luis Henriques <luis.henriques@canonical.com> --- drivers/cpuidle/cpuidle.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) -- 1.8.3.2