Fix ld uninitialized read of script ASSERT data structure

Fix ld uninitialized read of script ASSERT data structure

[Alan Modra]

Another bug that's been around for a while, but only noticed by me
this morning.  lang_assignment_statement serves both assignments and
asserts.

	* ldlang.c (open_input_bfds): Check that lang_assignment_statement
	is not an assert before referencing defsym.

diff --git a/ld/ChangeLog b/ld/ChangeLog
index cbe44a2..3883bcb 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,8 @@
+2017-03-07  Alan Modra  <amodra@gmail.com>
+
+	* ldlang.c (open_input_bfds): Check that lang_assignment_statement
+	is not an assert before referencing defsym.
+
 2017-03-05  Alan Modra  <amodra@gmail.com>
 
 	* testsuite/ld-elf/eh3.d: Adjust for eh_frame alignment change.
diff --git a/ld/ldlang.c b/ld/ldlang.c
index 1396c5b..ff6ef39 100644
--- a/ld/ldlang.c
+++ b/ld/ldlang.c
@@ -3374,7 +3374,8 @@ open_input_bfds (lang_statement_union_type *s, enum open_bfd_mode mode)
 #endif
 	  break;
 	case lang_assignment_statement_enum:
-	  if (s->assignment_statement.exp->assign.defsym)
+	  if (s->assignment_statement.exp->type.node_class != etree_assert
+	      && s->assignment_statement.exp->assign.defsym)
 	    /* This is from a --defsym on the command line.  */
 	    exp_fold_tree_no_dot (s->assignment_statement.exp);
 	  break;

-- 
Alan Modra
Australia Development Lab, IBM