[PATCH v3 2/2] iio: imu: inv_mpu6050: validate ACPI object types in asus_acpi_get_sensor_info()

[Tristan Madani <tristmd@gmail.com>]

From: Tristan Madani <tristan@talencesecurity.com>

asus_acpi_get_sensor_info() iterates through a nested ACPI package
structure without checking types at either level.  The outer object
returned by acpi_evaluate_object() and each inner element must be
validated as ACPI_TYPE_PACKAGE before accessing their package.count
and package.elements members.

Use acpi_evaluate_object_typed() to validate the outer object type
at evaluation time.  Add a type check for each inner element before
accessing its package contents.  Also replace kfree() with
ACPI_FREE() for the ACPI-allocated buffer.

Fixes: a35c5d1aa96a ("iio: imu: inv_mpu6050: Create mux clients for ACPI")
Cc: stable@vger.kernel.org
Signed-off-by: Tristan Madani <tristan@talencesecurity.com>
---
 drivers/iio/imu/inv_mpu6050/inv_mpu_acpi.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_acpi.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_acpi.c
index f7bce428d9eb4..e6a4de4fbffd2 100644
--- a/drivers/iio/imu/inv_mpu6050/inv_mpu_acpi.c
+++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_acpi.c
@@ -50,7 +50,8 @@ static int asus_acpi_get_sensor_info(struct acpi_device *adev,
 	union acpi_object *cpm;
 	int ret;
 
-	status = acpi_evaluate_object(adev->handle, "CNF0", NULL, &buffer);
+	status = acpi_evaluate_object_typed(adev->handle, "CNF0", NULL,
+					    &buffer, ACPI_TYPE_PACKAGE);
 	if (ACPI_FAILURE(status))
 		return -ENODEV;
 
@@ -60,6 +61,8 @@ static int asus_acpi_get_sensor_info(struct acpi_device *adev,
 		int j;
 
 		elem = &cpm->package.elements[i];
+		if (elem->type != ACPI_TYPE_PACKAGE)
+			continue;
 		for (j = 0; j < elem->package.count; ++j) {
 			union acpi_object *sub_elem;
 
@@ -76,7 +79,7 @@ static int asus_acpi_get_sensor_info(struct acpi_device *adev,
 		}
 	}
 	ret = cpm->package.count;
-	kfree(buffer.pointer);
+	ACPI_FREE(buffer.pointer);
 
 	return ret;
 }
-- 
2.47.3