[PATCH AUTOSEL 5.0 036/317] ACPI / property: fix handling of data_nodes in acpi_get_next_subnode()

Sasha Levin
2019-05-22T19:24:49Z

From: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>

[ Upstream commit 23583f7795025e3c783b680d906509366b0906ad ]

When the DSDT tables expose devices with subdevices and a set of
hierarchical _DSD properties, the data returned by
acpi_get_next_subnode() is incorrect, with the results suggesting a bad
pointer assignment. The parser works fine with device_nodes or
data_nodes, but not with a combination of the two.

The problem is traced to an invalid pointer used when jumping from
handling device_nodes to data nodes. The existing code looks for data
nodes below the last subdevice found instead of the common root. Fix
by forcing the acpi_device pointer to be derived from the same fwnode
for the two types of subnodes.

This same problem of handling device and data nodes was already fixed
in a similar way by 'commit bf4703fdd166 ("ACPI / property: fix data
node parsing in acpi_get_next_subnode()")' but broken later by 'commit
34055190b19 ("ACPI / property: Add fwnode_get_next_child_node()")', so
this should probably go to linux-stable all the way to 4.12

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/acpi/property.c | 8 ++++++++
1 file changed, 8 insertions(+)

diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c
index 77abe0ec40431..bd533f68b1dec 100644
--- a/drivers/acpi/property.c
+++ b/drivers/acpi/property.c
@@ -1031,6 +1031,14 @@ struct fwnode_handle *acpi_get_next_subnode(const struct fwnode_handle *fwnode,
const struct acpi_data_node *data = to_acpi_data_node(fwnode);
struct acpi_data_node *dn;

+ /*
+ * We can have a combination of device and data nodes, e.g. with
+ * hierarchical _DSD properties. Make sure the adev pointer is
+ * restored before going through data nodes, otherwise we will
+ * be looking for data_nodes below the last device found instead
+ * of the common fwnode shared by device_nodes and data_nodes.
+ */
+ adev = to_acpi_device_node(fwnode);
if (adev)
head = &adev->data.subnodes;
else if (data)
--
2.20.1