ACPICA: Tables: Fix invalid pointer accesses in acpi_tb_parse_root_table().

Linux XSDT validation mechanism backport has introduced a regreession:
  Commit: 671cc68dc61f029d44b43a681356078e02d8dab8
  Subject: ACPICA: Back port and refine validation of the XSDT root table.
There is a pointer still accessed after unmapping.

This patch fixes this issue.  Lv Zheng.

Fixes: 671cc68dc61f (ACPICA: Back port and refine validation of the XSDT root table.)
References: https://bugzilla.kernel.org/show_bug.cgi?id=73911
References: https://bugs.archlinux.org/task/39811
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Reported-and-tested-by: Bruce Chiarelli <mano155@gmail.com>
Reported-and-tested-by: Spyros Stathopoulos <spystath@gmail.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Cc: 3.14+ <stable@vger.kernel.org> # 3.14+
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

1 files changed, 5 insertions, 2 deletions

diff --git a/drivers/acpi/acpica/tbutils.c b/drivers/acpi/acpica/tbutils.c
index a4702eee91a8..9fb85f38de90 100644
--- a/drivers/acpi/acpica/tbutils.c
+++ b/drivers/acpi/acpica/tbutils.c
@@ -461,6 +461,7 @@ acpi_status __init acpi_tb_parse_root_table(acpi_physical_address rsdp_address)
         u32 table_count;
         struct acpi_table_header *table;
         acpi_physical_address address;
+        acpi_physical_address rsdt_address;
         u32 length;
         u8 *table_entry;
         acpi_status status;
@@ -488,11 +489,14 @@ acpi_status __init acpi_tb_parse_root_table(acpi_physical_address rsdp_address)
                  * as per the ACPI specification.
                  */
                 address = (acpi_physical_address) rsdp->xsdt_physical_address;
+                rsdt_address =
+                    (acpi_physical_address) rsdp->rsdt_physical_address;
                 table_entry_size = ACPI_XSDT_ENTRY_SIZE;
         } else {
                 /* Root table is an RSDT (32-bit physical addresses) */
 
                 address = (acpi_physical_address) rsdp->rsdt_physical_address;
+                rsdt_address = address;
                 table_entry_size = ACPI_RSDT_ENTRY_SIZE;
         }
 
@@ -515,8 +519,7 @@ acpi_status __init acpi_tb_parse_root_table(acpi_physical_address rsdp_address)
 
                         /* Fall back to the RSDT */
 
-                        address =
-                            (acpi_physical_address) rsdp->rsdt_physical_address;
+                        address = rsdt_address;
                         table_entry_size = ACPI_RSDT_ENTRY_SIZE;
                 }
         }