ACPI / PM: Walk physical_node_list under physical_node_lock

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
appropriate.

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Cc: All <stable@vger.kernel.org>

1 files changed, 8 insertions, 0 deletions

diff --git a/drivers/acpi/proc.c b/drivers/acpi/proc.c
index aa1227a7e3f2..04a13784dd20 100644
--- a/drivers/acpi/proc.c
+++ b/drivers/acpi/proc.c
@@ -311,6 +311,8 @@ acpi_system_wakeup_device_seq_show(struct seq_file *seq, void *offset)
                            dev->pnp.bus_id,
                            (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(struct seq_file *seq, void *offset)
                                 put_device(ldev);
                         }
                 }
+
+                mutex_unlock(&dev->physical_node_lock);
         }
         mutex_unlock(&acpi_device_lock);
         return 0;
@@ -347,12 +351,16 @@ static void physical_device_enable_wakeup(struct acpi_device *adev)
 {
         struct acpi_device_physical_node *entry;
 
+        mutex_lock(&adev->physical_node_lock);
+
         list_for_each_entry(entry,
                 &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