[PATCH 4.18 079/197] ACPICA: ACPICA: add status check for acpi_hw_read before assigning return value

[Greg Kroah-Hartman]

4.18-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Erik Schmauss <erik.schmauss@xxxxxxxxx>

[ Upstream commit f016b19a9275089a2ab06c2144567c2ad8d5d6ad ]

The value coming from acpi_hw_read() should not be used if it
returns an error code, so check the status returned by it before
using that value in two places in acpi_hw_register_read().

Reported-by: Mark Gross <mark.gross@xxxxxxxxx>
Signed-off-by: Erik Schmauss <erik.schmauss@xxxxxxxxx>
[ rjw: Changelog ]
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/acpi/acpica/hwregs.c |    9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

--- a/drivers/acpi/acpica/hwregs.c
+++ b/drivers/acpi/acpica/hwregs.c
@@ -528,13 +528,18 @@ acpi_status acpi_hw_register_read(u32 re
 
 		status =
 		    acpi_hw_read(&value64, &acpi_gbl_FADT.xpm2_control_block);
-		value = (u32)value64;
+		if (ACPI_SUCCESS(status)) {
+			value = (u32)value64;
+		}
 		break;
 
 	case ACPI_REGISTER_PM_TIMER:	/* 32-bit access */
 
 		status = acpi_hw_read(&value64, &acpi_gbl_FADT.xpm_timer_block);
-		value = (u32)value64;
+		if (ACPI_SUCCESS(status)) {
+			value = (u32)value64;
+		}
+
 		break;
 
 	case ACPI_REGISTER_SMI_COMMAND_BLOCK:	/* 8-bit access */