From 8bfda0d7d50f05de298abca907611be9a33d1626 Mon Sep 17 00:00:00 2001
From: Father Chrysostomos <sprout@cpan.org>
Date: Sat, 2 Nov 2013 06:17:23 -0700
Subject: [PATCH] Undefined lex sub used as inherited method crashes
MIME-Version: 1.0
Content-Type: text/plain; charset=utf8
Content-Transfer-Encoding: 8bit

Thanks to misuse of CvGV.

$ perl5.19.5 -XMfeature=:all -e 'my sub foo {} undef &foo; *UNIVERSAL::bar = \&foo; main->bar()'
Segmentation fault: 11

When deciding under which name to autoload the sub, we can’t assume
CvGV(that_sub) is a GV, as it may be null.
---
 gv.c          |  2 +-
 t/op/lexsub.t | 13 ++++++++++++-
 2 files changed, 13 insertions(+), 2 deletions(-)

diff --git a/gv.c b/gv.c
index e7ef9a7..2b88129 100644
--- a/gv.c
+++ b/gv.c
@@ -1057,7 +1057,7 @@ Perl_gv_fetchmethod_pvn_flags(pTHX_ HV *stash, const char *name, const STRLEN le
 	    GV* stubgv;
 	    GV* autogv;
 
-	    if (CvANON(cv))
+	    if (CvANON(cv) || !CvGV(cv))
 		stubgv = gv;
 	    else {
 		stubgv = CvGV(cv);
diff --git a/t/op/lexsub.t b/t/op/lexsub.t
index d717f42..0be305b 100644
--- a/t/op/lexsub.t
+++ b/t/op/lexsub.t
@@ -8,7 +8,7 @@ BEGIN {
     *bar::like = *like;
 }
 no warnings 'deprecated';
-plan 138;
+plan 139;
 
 # -------------------- Errors with feature disabled -------------------- #
 
@@ -716,3 +716,14 @@ like runperl(
      ),
      qr/Constant subroutine foo undefined at /,
     'constant undefinition warnings for lexical subs do not crash';
+
+{
+  my sub foo;
+  *AutoloadTestSuper::blah = \&foo;
+  sub AutoloadTestSuper::AUTOLOAD {
+    is $AutoloadTestSuper::AUTOLOAD, "AutoloadTestSuper::blah",
+      "Autoloading via inherited lex stub";
+  }
+  @AutoloadTest::ISA = AutoloadTestSuper::;
+  AutoloadTest->blah;
+}
-- 
2.7.4