ACPICA: Events: add a return on failure from acpi_hw_register_read

BugLink: https://bugs.launchpad.net/bugs/1775771

[ Upstream commit b4c0de31 ]

This ensures that acpi_ev_fixed_event_detect() does not use fixed_status
and and fixed_enable as uninitialized variables.
Signed-off-by: Erik Schmauss <erik.schmauss@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Juerg Haefliger <juergh@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>

drivers/acpi/acpica/evevent.c

@@ -204,6 +204,7 @@ u32 acpi_ev_fixed_event_detect(void)
 	u32 fixed_status;
 	u32 fixed_enable;
 	u32 i;
+	acpi_status status;
 
 	ACPI_FUNCTION_NAME(ev_fixed_event_detect);
 
@@ -211,8 +212,12 @@ u32 acpi_ev_fixed_event_detect(void)
 	 * Read the fixed feature status and enable registers, as all the cases
 	 * depend on their values. Ignore errors here.
 	 */
-	(void)acpi_hw_register_read(ACPI_REGISTER_PM1_STATUS, &fixed_status);
-	(void)acpi_hw_register_read(ACPI_REGISTER_PM1_ENABLE, &fixed_enable);
+	status = acpi_hw_register_read(ACPI_REGISTER_PM1_STATUS, &fixed_status);
+	status |=
+	    acpi_hw_register_read(ACPI_REGISTER_PM1_ENABLE, &fixed_enable);
+	if (ACPI_FAILURE(status)) {
+		return (int_status);
+	}
 
 	ACPI_DEBUG_PRINT((ACPI_DB_INTERRUPTS,
 			  "Fixed Event Block: Enable %08X Status %08X\n",