ACPI / ACPICA: Avoid crashing if _PRW is defined for the root object

Some ACPI BIOSes define _PRW for the root object which causes
acpi_setup_gpe_for_wake() to crash when trying to dereference the
bogus device_node pointer.  Avoid the crash by checking if
wake_device is not the root object before attempting to set up the
"implicit notify" mechanism for it.

The problem was introduced by commit bba63a296ffab20e08d9e8252d2f0d99
(ACPICA: Implicit notify support) that added the wake_device argument
to acpi_setup_gpe_for_wake().

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>

1 files changed, 26 insertions, 23 deletions

diff --git a/drivers/acpi/acpica/evxfgpe.c b/drivers/acpi/acpica/evxfgpe.c
index e9562a7cb2f..3b20a3401b6 100644
--- a/drivers/acpi/acpica/evxfgpe.c
+++ b/drivers/acpi/acpica/evxfgpe.c
@@ -212,37 +212,40 @@ acpi_setup_gpe_for_wake(acpi_handle wake_device,
                 return_ACPI_STATUS(AE_BAD_PARAMETER);
         }
 
-        /* Validate wake_device is of type Device */
-
-        device_node = ACPI_CAST_PTR(struct acpi_namespace_node, wake_device);
-        if (device_node->type != ACPI_TYPE_DEVICE) {
-                return_ACPI_STATUS(AE_BAD_PARAMETER);
-        }
-
         flags = acpi_os_acquire_lock(acpi_gbl_gpe_lock);
 
         /* Ensure that we have a valid GPE number */
 
         gpe_event_info = acpi_ev_get_gpe_event_info(gpe_device, gpe_number);
-        if (gpe_event_info) {
-                /*
-                 * If there is no method or handler for this GPE, then the
-                 * wake_device will be notified whenever this GPE fires (aka
-                 * "implicit notify") Note: The GPE is assumed to be
-                 * level-triggered (for windows compatibility).
-                 */
-                if ((gpe_event_info->flags & ACPI_GPE_DISPATCH_MASK) ==
-                    ACPI_GPE_DISPATCH_NONE) {
-                        gpe_event_info->flags =
-                            (ACPI_GPE_DISPATCH_NOTIFY |
-                             ACPI_GPE_LEVEL_TRIGGERED);
-                        gpe_event_info->dispatch.device_node = device_node;
-                }
+        if (!gpe_event_info) {
+                goto unlock_and_exit;
+        }
+
+        /*
+         * If there is no method or handler for this GPE, then the
+         * wake_device will be notified whenever this GPE fires (aka
+         * "implicit notify") Note: The GPE is assumed to be
+         * level-triggered (for windows compatibility).
+         */
+        if (((gpe_event_info->flags & ACPI_GPE_DISPATCH_MASK) ==
+              ACPI_GPE_DISPATCH_NONE) && (wake_device != ACPI_ROOT_OBJECT)) {
 
-                gpe_event_info->flags |= ACPI_GPE_CAN_WAKE;
-                status = AE_OK;
+                /* Validate wake_device is of type Device */
+
+                device_node = ACPI_CAST_PTR(struct acpi_namespace_node,
+                                            wake_device);
+                if (device_node->type != ACPI_TYPE_DEVICE) {
+                        goto unlock_and_exit;
+                }
+                gpe_event_info->flags = (ACPI_GPE_DISPATCH_NOTIFY |
+                                         ACPI_GPE_LEVEL_TRIGGERED);
+                gpe_event_info->dispatch.device_node = device_node;
         }
 
+        gpe_event_info->flags |= ACPI_GPE_CAN_WAKE;
+        status = AE_OK;
+
+ unlock_and_exit:
         acpi_os_release_lock(acpi_gbl_gpe_lock, flags);
         return_ACPI_STATUS(status);
 }