From 60f0e763a41636dd9284d4c0d56116fb7dfaae7d Mon Sep 17 00:00:00 2001
From: nobu <nobu@b2dd03c8-39d4-4d8f-98ff-823fe69b080e>
Date: Tue, 3 Apr 2018 06:57:44 +0000
Subject: proc.c: fix segfault when no singleton class

* proc.c (rb_obj_singleton_method): bail out if the receiver does
  not have the singleton class without accessing the origin class
  not to segfault.  [Bug #14658]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63068 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
---
 proc.c                   | 18 ++++++++++--------
 test/ruby/test_method.rb |  3 +++
 2 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/proc.c b/proc.c
index 551a135e02..b81d14ed46 100644
--- a/proc.c
+++ b/proc.c
@@ -1771,21 +1771,23 @@ VALUE
 rb_obj_singleton_method(VALUE obj, VALUE vid)
 {
     const rb_method_entry_t *me;
-    VALUE klass = RCLASS_ORIGIN(rb_singleton_class_get(obj));
+    VALUE klass = rb_singleton_class_get(obj);
     ID id = rb_check_id(&vid);
 
+    if (NIL_P(klass) || NIL_P(klass = RCLASS_ORIGIN(klass))) {
+      undef:
+	rb_name_err_raise("undefined singleton method `%1$s' for `%2$s'",
+			  obj, vid);
+    }
     if (!id) {
-	if (!NIL_P(klass) &&
-	    respond_to_missing_p(klass, obj, vid, FALSE)) {
+	if (respond_to_missing_p(klass, obj, vid, FALSE)) {
 	    id = rb_intern_str(vid);
 	    return mnew_missing(klass, obj, id, rb_cMethod);
 	}
-      undef:
-	rb_name_err_raise("undefined singleton method `%1$s' for `%2$s'",
-			  obj, vid);
+	goto undef;
     }
-    if (NIL_P(klass) ||
-	UNDEFINED_METHOD_ENTRY_P(me = rb_method_entry_at(klass, id)) ||
+    me = rb_method_entry_at(klass, id);
+    if (UNDEFINED_METHOD_ENTRY_P(me) ||
 	UNDEFINED_REFINED_METHOD_P(me->def)) {
 	vid = ID2SYM(id);
 	goto undef;
diff --git a/test/ruby/test_method.rb b/test/ruby/test_method.rb
index 67c24a8fd8..fe0171dd57 100644
--- a/test/ruby/test_method.rb
+++ b/test/ruby/test_method.rb
@@ -790,6 +790,9 @@ class TestMethod < Test::Unit::TestCase
     class << o; prepend Module.new; end
     m = assert_nothing_raised(NameError, bug14658) {o.singleton_method(:bar)}
     assert_equal(:bar, m.call, bug14658)
+
+    o = Object.new
+    assert_raise(NameError, bug14658) {o.singleton_method(:bar)}
   end
 
   Feature9783 = '[ruby-core:62212] [Feature #9783]'
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