ACPICA: Update parameter validation for data_table_region and load_table

ACPICA commit 51ab555e60b4a3de3cc4a846e86d0de255be441a

Add additional validation for the table signature and
the OEM strings. Eliminates buffer read overrun in data_table_region.
ACPICA BZ 1184.

Link: https://bugs.acpica.org/show_bug.cgi?id=1184
Link: https://github.com/acpica/acpica/commit/51ab555e
Signed-off-by: Bob Moore <robert.moore@intel.com>
Signed-off-by: Lv Zheng <lv.zheng@intel.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/acpi/acpica/tbutils.c

@@ -412,3 +412,36 @@ next_table:
 
 	return_ACPI_STATUS(AE_OK);
 }
+
+/*******************************************************************************
+ *
+ * FUNCTION:    acpi_is_valid_signature
+ *
+ * PARAMETERS:  signature           - Sig string to be validated
+ *
+ * RETURN:      TRUE if signature is correct length and has valid characters
+ *
+ * DESCRIPTION: Validate an ACPI table signature.
+ *
+ ******************************************************************************/
+
+u8 acpi_is_valid_signature(char *signature)
+{
+	u32 i;
+
+	/* Validate the signature length */
+
+	if (strlen(signature) != ACPI_NAME_SIZE) {
+		return (FALSE);
+	}
+
+	/* Validate each character in the signature */
+
+	for (i = 0; i < ACPI_NAME_SIZE; i++) {
+		if (!acpi_ut_valid_acpi_char(signature[i], i)) {
+			return (FALSE);
+		}
+	}
+
+	return (TRUE);
+}