linux: pslist: fix task credentials rendering

Author: gcmoreira

volatility3/framework/plugins/linux/pslist.py

@@ -179,6 +179,10 @@ def _get_file_output(self, task: interfaces.objects.ObjectInterface) -> str:
                 file_output = "VMA start matching task start_code not found"
         return file_output
 
+    @staticmethod
+    def _format_cred(cred):
+        return renderers.NotAvailableValue() if cred is None else cred
+
     def _generator(
         self,
         pid_filter: Callable[[Any], bool],
@@ -212,16 +216,21 @@ def _generator(
 
             task_fields = self.get_task_fields(task, decorate_comm)
 
+            task_uid = self._format_cred(task_fields.uid)
+            task_gid = self._format_cred(task_fields.gid)
+            task_euid = self._format_cred(task_fields.euid)
+            task_egid = self._format_cred(task_fields.egid)
+
             yield 0, (
                 format_hints.Hex(task_fields.offset),
                 task_fields.user_pid,
                 task_fields.user_tid,
                 task_fields.user_ppid,
                 task_fields.name,
-                task_fields.uid or renderers.NotAvailableValue(),
-                task_fields.gid or renderers.NotAvailableValue(),
-                task_fields.euid or renderers.NotAvailableValue(),
-                task_fields.egid or renderers.NotAvailableValue(),
+                task_uid,
+                task_gid,
+                task_euid,
+                task_egid,
                 task_fields.creation_time or renderers.NotAvailableValue(),
                 file_output,
             )