Messages in this thread | | | Subject | Re: [PATCH] ACPI / property: fix handling of data_nodes in acpi_get_next_subnode() | From | Pierre-Louis Bossart <> | Date | Tue, 30 Apr 2019 11:41:50 -0500 |
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On 4/30/19 11:30 AM, Andy Shevchenko wrote: > On Tue, Apr 30, 2019 at 10:52:29AM -0500, Pierre-Louis Bossart wrote: >> 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 > > Period is missed in above sentence. > > I think it make sense to add Fixes: tag.
Thanks Andy for the review. I hesitated to add a fixes tag. The line about resetting the adev pointer was indeed removed in the latter commit, but there were a slew of other changes done later by Sakari on hierarchical _DSD so it's quite complicated to say when this was last fully functional.
> > Nevertheless, > Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> > > Thank you for fixing this interesting issue! > >> >> Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com> >> --- >> drivers/acpi/property.c | 10 ++++++++++ >> 1 file changed, 10 insertions(+) >> >> diff --git a/drivers/acpi/property.c b/drivers/acpi/property.c >> index 5815356ea6ad..efc74f912f39 100644 >> --- a/drivers/acpi/property.c >> +++ b/drivers/acpi/property.c >> @@ -943,6 +943,16 @@ 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) >> -- >> 2.17.1 >> >
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