1 files changed, 22 insertions, 5 deletions

diff --git a/drivers/acpi/acpica/tbinstal.c b/drivers/acpi/acpica/tbinstal.c
index 48db0944ce4a..62365f6075dd 100644
--- a/drivers/acpi/acpica/tbinstal.c
+++ b/drivers/acpi/acpica/tbinstal.c
@@ -126,12 +126,29 @@ acpi_tb_add_table(struct acpi_table_desc *table_desc, u32 *table_index)
         }
 
         /*
-         * Originally, we checked the table signature for "SSDT" or "PSDT" here.
-         * Next, we added support for OEMx tables, signature "OEM".
-         * Valid tables were encountered with a null signature, so we've just
-         * given up on validating the signature, since it seems to be a waste
-         * of code. The original code was removed (05/2008).
+         * 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 ((table_desc->pointer->signature[0] != 0x00) &&
+            (!ACPI_COMPARE_NAME(table_desc->pointer->signature, ACPI_SIG_SSDT))
+            && (ACPI_STRNCMP(table_desc->pointer->signature, "OEM", 3))) {
+                ACPI_ERROR((AE_INFO,
+                            "Table has invalid signature [%4.4s] (0x%8.8X), must be SSDT or OEMx",
+                            acpi_ut_valid_acpi_name(*(u32 *)table_desc->
+                                                    pointer->
+                                                    signature) ? table_desc->
+                            pointer->signature : "????",
+                            *(u32 *)table_desc->pointer->signature));
+
+                return_ACPI_STATUS(AE_BAD_SIGNATURE);
+        }
 
         (void)acpi_ut_acquire_mutex(ACPI_MTX_TABLES);