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Commit a104b4d4 authored by Rafael J. Wysocki's avatar Rafael J. Wysocki
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ACPI / bind: Use (put|get)_device() on ACPI device objects too 



When associating a "physical" device with an ACPI device object
acpi_bind_one() only uses get_device() to increment the reference
counter of the former, but there is no reason not to do that with
the latter too.  Among other things, that may help to avoid
use-after-free when an ACPI device object is freed without calling
acpi_unbind_one() for all "physical" devices associated with it
(that only can happen in buggy code, but then it's better if the
kernel doesn't crash as a result of a bug).

For this reason, modify acpi_bind_one() to apply get_device() to
the ACPI device object too and update acpi_unbind_one() to drop
that reference using put_device() as appropriate.

Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
Acked-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-by: default avatarLan Tianyu <tianyu.lan@intel.com>
parent 3a83f992

drivers/acpi/glue.c

+5 −1
Original line number Diff line number Diff line
@@ -217,6 +217,7 @@ int acpi_bind_one(struct device *dev, acpi_handle handle) 
	if (!acpi_dev)

		return -EINVAL;



	get_device(&acpi_dev->dev);

	get_device(dev);

	physical_node = kzalloc(sizeof(*physical_node), GFP_KERNEL);

	if (!physical_node) {
@@ -243,6 +244,7 @@ int acpi_bind_one(struct device *dev, acpi_handle handle) 
				goto err;



			put_device(dev);

			put_device(&acpi_dev->dev);

			return 0;

		}

		if (pn->node_id == node_id) {
@@ -282,6 +284,7 @@ int acpi_bind_one(struct device *dev, acpi_handle handle) 
 err:

	ACPI_COMPANION_SET(dev, NULL);

	put_device(dev);

	put_device(&acpi_dev->dev);

	return retval;

}

EXPORT_SYMBOL_GPL(acpi_bind_one);
@@ -307,8 +310,9 @@ int acpi_unbind_one(struct device *dev) 
			sysfs_remove_link(&acpi_dev->dev.kobj, physnode_name);

			sysfs_remove_link(&dev->kobj, "firmware_node");

			ACPI_COMPANION_SET(dev, NULL);

			/* acpi_bind_one() increase refcnt by one. */

			/* Drop references taken by acpi_bind_one(). */

			put_device(dev);

			put_device(&acpi_dev->dev);

			kfree(entry);

			break;

		}