[PATCH] ACPI / PM: Walk physical_node_list under physical_node_lock

From: Rafael J. Wysocki
Date: Mon Aug 05 2013 - 09:59:57 EST

From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>

The list of physical devices corresponding to an ACPI device
object is walked by acpi_system_wakeup_device_seq_show() and
physical_device_enable_wakeup() without taking that object's
physical_node_lock mutex. Since each of those functions may be
run at any time as a result of a user space action, the lack of
appropriate locking in them may lead to a kernel crash if that
happens during device hot-add or hot-remove involving the device
object in question.

Fix the issue by modifying acpi_system_wakeup_device_seq_show() and
physical_device_enable_wakeup() to use physical_node_lock as

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Cc: All <stable@xxxxxxxxxxxxxxx>

This is urgent stuff, so if anyone has any objections against this or sees
any problems with it, please let me know immediately.


drivers/acpi/proc.c | 8 ++++++++
1 file changed, 8 insertions(+)

Index: linux-pm/drivers/acpi/proc.c
--- linux-pm.orig/drivers/acpi/proc.c
+++ linux-pm/drivers/acpi/proc.c
@@ -311,6 +311,8 @@ acpi_system_wakeup_device_seq_show(struc
(u32) dev->wakeup.sleep_state);

+ mutex_lock(&dev->physical_node_lock);
if (!dev->physical_node_count) {
seq_printf(seq, "%c%-8s\n",
dev->wakeup.flags.run_wake ? '*' : ' ',
@@ -338,6 +340,8 @@ acpi_system_wakeup_device_seq_show(struc
+ mutex_unlock(&dev->physical_node_lock);
return 0;
@@ -347,12 +351,16 @@ static void physical_device_enable_wakeu
struct acpi_device_physical_node *entry;

+ mutex_lock(&adev->physical_node_lock);
&adev->physical_node_list, node)
if (entry->dev && device_can_wakeup(entry->dev)) {
bool enable = !device_may_wakeup(entry->dev);
device_set_wakeup_enable(entry->dev, enable);
+ mutex_unlock(&adev->physical_node_lock);

static ssize_t

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