ACPI: sysfs: validate return type of _STR method

Only buffer objects are valid return values of _STR.

If something else is returned description_show() will access invalid
memory.

Fixes: d1efe3c324ea ("ACPI: Add new sysfs interface to export device description")
Cc: All applicable <stable@vger.kernel.org>
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
Link: https://patch.msgid.link/20240709-acpi-sysfs-groups-v2-1-058ab0667fa8@weissschuh.net
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

diff --git a/drivers/acpi/device_sysfs.c b/drivers/acpi/device_sysfs.c
index 23373faa35ecd6a48e13090d2be3ca9a4a6e7c62..95a19e3569c83fc6f5caf350925811bdaac95cce 100644 (file)
--- a/drivers/acpi/device_sysfs.c
+++ b/drivers/acpi/device_sysfs.c
@@ -540,8 +540,9 @@ int acpi_device_setup_files(struct acpi_device *dev)
         * If device has _STR, 'description' file is created
         */
        if (acpi_has_method(dev->handle, "_STR")) {
-               status = acpi_evaluate_object(dev->handle, "_STR",
-                                       NULL, &buffer);
+               status = acpi_evaluate_object_typed(dev->handle, "_STR",
+                                                   NULL, &buffer,
+                                                   ACPI_TYPE_BUFFER);
                if (ACPI_FAILURE(status))
                        buffer.pointer = NULL;
                dev->pnp.str_obj = buffer.pointer;