[PATCH] hwmon: (hp-wmi-sensors) Accept raw WMI strings in numeric sensor properties

[PATCH] hwmon: (hp-wmi-sensors) Accept raw WMI strings in numeric sensor properties

[Muhammad Bilal]

Commit c9ba59258094 ("hwmon: (hp-wmi-sensors) Fix failure to load on
EliteDesk 800 G6") added support for BIOS-reported WMI strings that
are encoded as a length-prefixed UTF-16 ACPI_TYPE_BUFFER instead of
a plain ACPI_TYPE_STRING. check_wobj(), extract_acpi_value(), and
update_numeric_sensor_from_wobj() were all updated to recognize and
decode this encoding.

check_numeric_sensor_wobj() was missed. It performs its own
independent, stricter type check on every property of a
HPBIOS_BIOSNumericSensor instance:

	type = elements[i].type;
	valid_type = hp_wmi_property_map[prop];
	if (type != valid_type)
		return -EINVAL;

and, separately, on each entry of PossibleStates[]:

	type = elements[++i].type;
	if (type != valid_type)
		return -EINVAL;

Neither site has the ACPI_TYPE_BUFFER exception that check_wobj()
gained. Both populate_numeric_sensor_from_wobj() and
update_numeric_sensor_from_wobj() call check_numeric_sensor_wobj()
first and bail out on its -EINVAL before ever reaching the
buffer-aware code in extract_acpi_value() or the CurrentState
handling added to update_numeric_sensor_from_wobj(). So on any BIOS
that reports Name, Description, OtherSensorType, PossibleStates, or
CurrentState of a numeric sensor as a raw WMI string buffer, probing
that sensor fails outright, and the buffer-decoding path added for
it is unreachable dead code.

Give check_numeric_sensor_wobj() the same is_raw_wmi_string()
exception as check_wobj(), in both the main property loop and the
PossibleStates[] sub-loop.

Fixes: c9ba59258094 ("hwmon: (hp-wmi-sensors) Fix failure to load on EliteDesk 800 G6")
Cc: stable@vger.kernel.org
Signed-off-by: Muhammad Bilal <meatuni001@gmail.com>
---
 drivers/hwmon/hp-wmi-sensors.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/hwmon/hp-wmi-sensors.c b/drivers/hwmon/hp-wmi-sensors.c
index 03c684b..a4bb4da 100644
--- a/drivers/hwmon/hp-wmi-sensors.c
+++ b/drivers/hwmon/hp-wmi-sensors.c
@@ -631,8 +631,14 @@ static int check_numeric_sensor_wobj(const union acpi_object *wobj,
 	for (i = 0; i < elem_count && prop <= last_prop; i++, prop++) {
 		type = elements[i].type;
 		valid_type = hp_wmi_property_map[prop];
-		if (type != valid_type)
+		if (type != valid_type) {
+			if (type == ACPI_TYPE_BUFFER &&
+			    valid_type == ACPI_TYPE_STRING &&
+			    is_raw_wmi_string(elements[i].buffer.pointer,
+					      elements[i].buffer.length))
+				continue;
 			return -EINVAL;
+		}
 
 		switch (prop) {
 		case HP_WMI_PROPERTY_OPERATIONAL_STATUS:
@@ -651,8 +657,13 @@ static int check_numeric_sensor_wobj(const union acpi_object *wobj,
 			/* PossibleStates[0] has already been type-checked. */
 			for (j = 0; i + 1 < elem_count && j + 1 < count; j++) {
 				type = elements[++i].type;
-				if (type != valid_type)
+				if (type != valid_type) {
+					if (type == ACPI_TYPE_BUFFER &&
+					    is_raw_wmi_string(elements[i].buffer.pointer,
+							      elements[i].buffer.length))
+						continue;
 					return -EINVAL;
+				}
 			}
 
 			/* Old variant: BaseUnits follows PossibleStates[]. */
-- 
2.43.0