[ruby-dev:40452] [bug:trunk] Invalid read of size 4 by redefining load

以下のように load 中に load を再定義すると、変なところをアクセスするのが
valgrind で観測されます。

% cat tst.rb
module Kernel
  def load(*args)
  end
end
raise
% valgrind ./ruby -ve 'load "tst.rb"'
==12820== Memcheck, a memory error detector.
==12820== Copyright (C) 2002-2007, and GNU GPL'd, by Julian Seward et al.
==12820== Using LibVEX rev 1854, a library for dynamic binary translation.
==12820== Copyright (C) 2004-2007, and GNU GPL'd, by OpenWorks LLP.
==12820== Using valgrind-3.3.1-Debian, a dynamic binary
instrumentation framework.
==12820== Copyright (C) 2000-2007, and GNU GPL'd, by Julian Seward et al.
==12820== For more details, rerun with: -v
==12820==
ruby 1.9.2dev (2010-02-21 trunk 26723) [i686-linux]
tst.rb:2: warning: method redefined; discarding old load
==12820== Invalid read of size 4
==12820==    at 0x814EA8F: vm_backtrace_each (vm.c:737)
==12820==    by 0x814EBF2: vm_backtrace (vm.c:771)
==12820==    by 0x814D1EE: rb_make_backtrace (vm_eval.c:1590)
==12820==    by 0x805EB30: setup_exception (eval.c:378)
==12820==    by 0x805F142: rb_raise_jump (eval.c:573)
==12820==    by 0x805EF34: rb_f_raise (eval.c:503)
==12820==    by 0x8147821: call_cfunc (vm_insnhelper.c:290)
==12820==    by 0x81476F9: vm_call_cfunc (vm_insnhelper.c:377)
==12820==    by 0x8146CC2: vm_call_method (vm_insnhelper.c:500)
==12820==    by 0x81428F8: vm_exec_core (insns.def:999)
==12820==    by 0x814F7C5: vm_exec (vm.c:1132)
==12820==    by 0x814FF65: rb_iseq_eval (vm.c:1359)
==12820==  Address 0x434c014 is 4 bytes inside a block of size 16 free'd
==12820==    at 0x4022B8A: free (vg_replace_malloc.c:323)
==12820==    by 0x8063B6E: vm_xfree (gc.c:731)
==12820==    by 0x8063CC5: ruby_xfree (gc.c:779)
==12820==    by 0x814848B: rb_free_method_entry (vm_method.c:141)
==12820==    by 0x814881B: rb_add_method_def (vm_method.c:213)
==12820==    by 0x81489EC: rb_add_method (vm_method.c:263)
==12820==    by 0x8150D8E: vm_define_method (vm.c:1846)
==12820==    by 0x8150E3E: m_core_define_method (vm.c:1862)
==12820==    by 0x81478B8: call_cfunc (vm_insnhelper.c:302)
==12820==    by 0x81476F9: vm_call_cfunc (vm_insnhelper.c:377)
==12820==    by 0x8146CC2: vm_call_method (vm_insnhelper.c:500)
==12820==    by 0x81428F8: vm_exec_core (insns.def:999)
==12820==
==12820== Invalid read of size 4
==12820==    at 0x814EAAD: vm_backtrace_each (vm.c:740)
==12820==    by 0x814EBF2: vm_backtrace (vm.c:771)
==12820==    by 0x814D1EE: rb_make_backtrace (vm_eval.c:1590)
==12820==    by 0x805EB30: setup_exception (eval.c:378)
==12820==    by 0x805F142: rb_raise_jump (eval.c:573)
==12820==    by 0x805EF34: rb_f_raise (eval.c:503)
==12820==    by 0x8147821: call_cfunc (vm_insnhelper.c:290)
==12820==    by 0x81476F9: vm_call_cfunc (vm_insnhelper.c:377)
==12820==    by 0x8146CC2: vm_call_method (vm_insnhelper.c:500)
==12820==    by 0x81428F8: vm_exec_core (insns.def:999)
==12820==    by 0x814F7C5: vm_exec (vm.c:1132)
==12820==    by 0x814FF65: rb_iseq_eval (vm.c:1359)
==12820==  Address 0x434c018 is 8 bytes inside a block of size 16 free'd
==12820==    at 0x4022B8A: free (vg_replace_malloc.c:323)
==12820==    by 0x8063B6E: vm_xfree (gc.c:731)
==12820==    by 0x8063CC5: ruby_xfree (gc.c:779)
==12820==    by 0x814848B: rb_free_method_entry (vm_method.c:141)
==12820==    by 0x814881B: rb_add_method_def (vm_method.c:213)
==12820==    by 0x81489EC: rb_add_method (vm_method.c:263)
==12820==    by 0x8150D8E: vm_define_method (vm.c:1846)
==12820==    by 0x8150E3E: m_core_define_method (vm.c:1862)
==12820==    by 0x81478B8: call_cfunc (vm_insnhelper.c:302)
==12820==    by 0x81476F9: vm_call_cfunc (vm_insnhelper.c:377)
==12820==    by 0x8146CC2: vm_call_method (vm_insnhelper.c:500)
==12820==    by 0x81428F8: vm_exec_core (insns.def:999)
tst.rb:5:in `<top (required)>': unhandled exception
        from -e:1:in `load'
        from -e:1:in `<main>'
==12820==
==12820== ERROR SUMMARY: 2 errors from 2 contexts (suppressed: 29 from 1)
==12820== malloc/free: in use at exit: 615,707 bytes in 14,666 blocks.
==12820== malloc/free: 16,023 allocs, 1,357 frees, 1,662,183 bytes allocated.
==12820== For counts of detected errors, rerun with: -v
==12820== searching for pointers to 14,666 not-freed blocks.
==12820== checked 451,824 bytes.
==12820==
==12820== LEAK SUMMARY:
==12820==    definitely lost: 467,917 bytes in 9,809 blocks.
==12820==      possibly lost: 0 bytes in 0 blocks.
==12820==    still reachable: 147,790 bytes in 4,857 blocks.
==12820==         suppressed: 0 bytes in 0 blocks.
==12820== Rerun with --leak-check=full to see details of leaked memory.
-- 
[田中 哲][たなか あきら][Tanaka Akira]