[Update][PATCH 1/5] ACPI / scan: Prevent device add uevents from racing with user space

Rafael J. Wysocki
2013-01-23T17:56:48Z

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

ACPI core adds sysfs device files after the given devices have been
registered with device_register(), which is not appropriate, because
it may lead to race conditions with user space tools using those
files.

Fix the problem by delaying the KOBJ_ADD uevent for ACPI devices
until after all of the devices' sysfs files have been created.

This also fixes a use-after-free in acpi_device_unregister().

Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
---
drivers/acpi/internal.h | 5 +++--
drivers/acpi/power.c | 3 ++-
drivers/acpi/scan.c | 20 +++++++++++++++-----
3 files changed, 20 insertions(+), 8 deletions(-)

Index: linux-pm/drivers/acpi/internal.h
===================================================================
--- linux-pm.orig/drivers/acpi/internal.h
+++ linux-pm/drivers/acpi/internal.h
@@ -40,10 +40,11 @@ static inline void acpi_debugfs_init(voi
#define ACPI_STA_DEFAULT (ACPI_STA_DEVICE_PRESENT | ACPI_STA_DEVICE_ENABLED | \
ACPI_STA_DEVICE_UI | ACPI_STA_DEVICE_FUNCTIONING)

-int acpi_device_register(struct acpi_device *device,
- void (*release)(struct device *));
+int acpi_device_add(struct acpi_device *device,
+ void (*release)(struct device *));
void acpi_init_device_object(struct acpi_device *device, acpi_handle handle,
int type, unsigned long long sta);
+void acpi_device_add_finalize(struct acpi_device *device);
void acpi_free_ids(struct acpi_device *device);

/* --------------------------------------------------------------------------
Index: linux-pm/drivers/acpi/power.c
===================================================================
--- linux-pm.orig/drivers/acpi/power.c
+++ linux-pm/drivers/acpi/power.c
@@ -719,13 +719,14 @@ int acpi_add_power_resource(acpi_handle
acpi_device_bid(device), state ? "on" : "off");

device->flags.match_driver = true;
- result = acpi_device_register(device, acpi_release_power_resource);
+ result = acpi_device_add(device, acpi_release_power_resource);
if (result)
goto err;

mutex_lock(&power_resource_list_lock);
list_add(&resource->list_node, &acpi_power_resource_list);
mutex_unlock(&power_resource_list_lock);
+ acpi_device_add_finalize(device);
return 0;

err:
Index: linux-pm/drivers/acpi/scan.c
===================================================================
--- linux-pm.orig/drivers/acpi/scan.c
+++ linux-pm/drivers/acpi/scan.c
@@ -633,8 +633,8 @@ struct bus_type acpi_bus_type = {
.uevent = acpi_device_uevent,
};

-int acpi_device_register(struct acpi_device *device,
- void (*release)(struct device *))
+int acpi_device_add(struct acpi_device *device,
+ void (*release)(struct device *))
{
int result;
struct acpi_device_bus_id *acpi_device_bus_id, *new_bus_id;
@@ -704,7 +704,7 @@ int acpi_device_register(struct acpi_dev
device->dev.parent = &device->parent->dev;
device->dev.bus = &acpi_bus_type;
device->dev.release = release;
- result = device_register(&device->dev);
+ result = device_add(&device->dev);
if (result) {
dev_err(&device->dev, "Error registering device\n");
goto err;
@@ -743,12 +743,13 @@ static void acpi_device_unregister(struc

acpi_power_add_remove_device(device, false);
acpi_device_remove_files(device);
- device_unregister(&device->dev);
+ device_del(&device->dev);
/*
* Drop the reference counts of all power resources the device depends
* on and turn off the ones that have no more references.
*/
acpi_power_transition(device, ACPI_STATE_D3_COLD);
+ put_device(&device->dev);
}

/* --------------------------------------------------------------------------
@@ -1390,6 +1391,14 @@ void acpi_init_device_object(struct acpi
acpi_device_get_busid(device);
acpi_device_set_id(device);
acpi_bus_get_flags(device);
+ device_initialize(&device->dev);
+ dev_set_uevent_suppress(&device->dev, true);
+}
+
+void acpi_device_add_finalize(struct acpi_device *device)
+{
+ dev_set_uevent_suppress(&device->dev, false);
+ kobject_uevent(&device->dev.kobj, KOBJ_ADD);
}

static int acpi_add_single_object(struct acpi_device **child,
@@ -1411,13 +1420,14 @@ static int acpi_add_single_object(struct
acpi_bus_get_wakeup_device_flags(device);

device->flags.match_driver = match_driver;
- result = acpi_device_register(device, acpi_device_release);
+ result = acpi_device_add(device, acpi_device_release);
if (result) {
acpi_device_release(&device->dev);
return result;
}

acpi_power_add_remove_device(device, true);
+ acpi_device_add_finalize(device);
acpi_get_name(handle, ACPI_FULL_PATHNAME, &buffer);
ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Added %s [%s] parent %s\n",
dev_name(&device->dev), (char *) buffer.pointer,