ACPICA: Tables: Do not validate signature for dynamic table load

ACPICA commit d3c944f2cdc8c7e847b7942b1864f285189f7bce

Windows seems to allow arbitrary table signatures for Load/load_table
opcodes:
  ACPI BIOS Error (bug): Table has invalid signature [PRAD] (0x44415250)
So this patch removes dynamic load signature checks. However we need to
find a way to avoid table loading against tables like MADT. This is not
covered by this commit.

This Windows behavior has been validated on link #1. An end user bug
report can also be found on link #2.

This patch also includes simple cleanup for static load signature check
code. Reported by Ye Xiaolong, Fixed by Lv Zheng.

Link: https://github.com/acpica/acpica/commit/d3c944f2
Link: https://github.com/acpica/acpica/pull/121 [#1]
Link: https://bugzilla.kernel.org/show_bug.cgi?id=118601 [#2]
Reported-by: Ye Xiaolong <xiaolong.ye@intel.com>
Reported-by: Olga Uhina <olga.uhina@gmail.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

2 files changed, 1 insertions, 29 deletions

diff --git a/drivers/acpi/acpica/tbinstal.c b/drivers/acpi/acpica/tbinstal.c
index ee745152f25b..9d212967fad8 100644
--- a/drivers/acpi/acpica/tbinstal.c
+++ b/drivers/acpi/acpica/tbinstal.c
@@ -222,34 +222,6 @@ acpi_tb_install_standard_table(acpi_physical_address address,
         (void)acpi_ut_acquire_mutex(ACPI_MTX_TABLES);
 
         if (reload) {
-                /*
-                 * Validate the incoming table signature.
-                 *
-                 * 1) Originally, we checked the table signature for "SSDT" or "PSDT".
-                 * 2) We added support for OEMx tables, signature "OEM".
-                 * 3) Valid tables were encountered with a null signature, so we just
-                 *    gave up on validating the signature, (05/2008).
-                 * 4) We encountered non-AML tables such as the MADT, which caused
-                 *    interpreter errors and kernel faults. So now, we once again allow
-                 *    only "SSDT", "OEMx", and now, also a null signature. (05/2011).
-                 */
-                if ((new_table_desc.signature.ascii[0] != 0x00) &&
-                    (!ACPI_COMPARE_NAME
-                     (&new_table_desc.signature, ACPI_SIG_SSDT))
-                    && (strncmp(new_table_desc.signature.ascii, "OEM", 3))) {
-                        ACPI_BIOS_ERROR((AE_INFO,
-                                         "Table has invalid signature [%4.4s] (0x%8.8X), "
-                                         "must be SSDT or OEMx",
-                                         acpi_ut_valid_nameseg(new_table_desc.
-                                                               signature.
-                                                               ascii) ?
-                                         new_table_desc.signature.
-                                         ascii : "????",
-                                         new_table_desc.signature.integer));
-
-                        status = AE_BAD_SIGNATURE;
-                        goto unlock_and_exit;
-                }
 
                 /* Check if table is already registered */
 
diff --git a/drivers/acpi/acpica/tbxfload.c b/drivers/acpi/acpica/tbxfload.c
index b71ce3b817ea..d81f442228b8 100644
--- a/drivers/acpi/acpica/tbxfload.c
+++ b/drivers/acpi/acpica/tbxfload.c
@@ -206,7 +206,7 @@ acpi_status acpi_tb_load_namespace(void)
         for (i = 0; i < acpi_gbl_root_table_list.current_table_count; ++i) {
                 table = &acpi_gbl_root_table_list.tables[i];
 
-                if (!acpi_gbl_root_table_list.tables[i].address ||
+                if (!table->address ||
                     (!ACPI_COMPARE_NAME(table->signature.ascii, ACPI_SIG_SSDT)
                      && !ACPI_COMPARE_NAME(table->signature.ascii,
                                            ACPI_SIG_PSDT)