Bug #4322: valgrind report error for uncaught throw

• Status: Closed
• Assignee: -
• Target version: -
• ruby -v: ruby 1.9.3dev (2011-01-25 trunk 30653) [i686-linux]

[nagachika (Tomoyuki Chikanaga)]

=begin
以下のようなスクリプトを valgrind を使って実行するとエラーが報告されます。

script

GC.stress = true
throw :tag

message

==1141== Conditional jump or move depends on uninitialised value(s)
==1141== at 0x40276EB: strlen (mc_replace_strmem.c:242)
==1141== by 0x81031DB: BSD_vfprintf (vsnprintf.c:961)
==1141== by 0x81070C4: rb_vsprintf (sprintf.c:1175)
==1141== by 0x81B6628: rb_raise (error.c:1524)
==1141== by 0x8160964: rb_f_throw (vm_eval.c:1441)
==1141== by 0x815D0EC: call_cfunc (vm_insnhelper.c:316)
==1141== by 0x8162468: vm_call_method (vm_insnhelper.c:403)
==1141== by 0x8163C5B: vm_exec_core (insns.def:1010)
==1141== by 0x816947B: vm_exec (vm.c:1150)
==1141== by 0x81697D9: rb_iseq_eval_main (vm.c:1391)
==1141== by 0x805B861: ruby_exec_internal (eval.c:225)
==1141== by 0x805D331: ruby_run_node (eval.c:272)
==1141==
==1141== Conditional jump or move depends on uninitialised value(s)
==1141== at 0x40276F7: strlen (mc_replace_strmem.c:242)
==1141== by 0x81031DB: BSD_vfprintf (vsnprintf.c:961)
==1141== by 0x81070C4: rb_vsprintf (sprintf.c:1175)
==1141== by 0x81B6628: rb_raise (error.c:1524)
==1141== by 0x8160964: rb_f_throw (vm_eval.c:1441)
==1141== by 0x815D0EC: call_cfunc (vm_insnhelper.c:316)
==1141== by 0x8162468: vm_call_method (vm_insnhelper.c:403)
==1141== by 0x8163C5B: vm_exec_core (insns.def:1010)
==1141== by 0x816947B: vm_exec (vm.c:1150)
==1141== by 0x81697D9: rb_iseq_eval_main (vm.c:1391)
==1141== by 0x805B861: ruby_exec_internal (eval.c:225)
==1141== by 0x805D331: ruby_run_node (eval.c:272)
test.rb:2:in throw'==1141== ==1141== Conditional jump or move depends on uninitialised value(s) ==1141== at 0x4027B28: memchr (mc_replace_strmem.c:354) ==1141== by 0x805C2E9: error_print (eval_error.c:144) ==1141== by 0x805CA9A: error_handle (eval_error.c:270) ==1141== by 0x805D05B: ruby_cleanup (eval.c:163) ==1141== by 0x805D339: ruby_run_node (eval.c:265) ==1141== by 0x805AC2F: main (main.c:38) : ==1141== ==1141== Syscall param write(buf) points to uninitialised byte(s) ==1141== at 0x40007F2: (within /lib/ld-2.9.so) ==1141== by 0x4125C95: _IO_file_xsputn (in /lib/tls/i686/cmov/libc-2.9.so) ==1141== by 0x411B6E9: fwrite (in /lib/tls/i686/cmov/libc-2.9.so) ==1141== by 0x8073A4A: rb_write_error2 (io.c:6324) ==1141== by 0x805C314: error_print (eval_error.c:149) ==1141== by 0x805CA9A: error_handle (eval_error.c:270) ==1141== by 0x805D05B: ruby_cleanup (eval.c:163) ==1141== by 0x805D339: ruby_run_node (eval.c:265) ==1141== by 0x805AC2F: main (main.c:38) ==1141== Address 0x4593d37 is 15 bytes inside a block of size 121 alloc'd ==1141== at 0x40270FC: realloc (vg_replace_malloc.c:429) ==1141== by 0x8068D0E: vm_xrealloc (gc.c:727) ==1141== by 0x811F726: rb_str_resize (string.c:1762) ==1141== by 0x81011D1: ruby__sfvwrite (sprintf.c:1148) ==1141== by 0x81021DD: BSD_vfprintf (vsnprintf.c:333) ==1141== by 0x81070C4: rb_vsprintf (sprintf.c:1175) ==1141== by 0x81B6628: rb_raise (error.c:1524) ==1141== by 0x8160964: rb_f_throw (vm_eval.c:1441) ==1141== by 0x815D0EC: call_cfunc (vm_insnhelper.c:316) ==1141== by 0x8162468: vm_call_method (vm_insnhelper.c:403) ==1141== by 0x8163C5B: vm_exec_core (insns.def:1010) ==1141== by 0x816947B: vm_exec (vm.c:1150) uncaught throw :tag (ArgumentError) from test.rb:2:in '
=end

[naruse (Yui NARUSE)]

=begin
ちょっと古いものだと確かに再現したのですが、r30653 時点で直ってるように見えます
=end

[naruse (Yui NARUSE)]

=begin
あれ、リビジョン同じだな。configureで--with-valgrindは指定してますよね?
=end

[nagachika (Tomoyuki Chikanaga)]

=begin
はい --with-valgrind は付けてます。
すみません、書き忘れてましたが optflags=-O3 を付けてビルドした時に発生します(gcc 4.3.3)。

実はテストケースはソースから逆算して作ったので(#4321 も同様)、以下の RB_GC_GUARD 追加で直ることを確認しています。
すぐ修正するつもりだったのですけど前準備に手間取って一晩寝かせてしまいました。

diff --git a/vm_eval.c b/vm_eval.c
index c67e54c..0dcbafa 100644
--- a/vm_eval.c
+++ b/vm_eval.c
@@ -1438,6 +1438,7 @@ rb_throw_obj(VALUE tag, VALUE value)
}
if (!tt) {
VALUE desc = rb_inspect(tag);

•   RB_GC_GUARD(desc);
    rb_raise(rb_eArgError, "uncaught throw %s", RSTRING_PTR(desc));
  

  }
  rb_trap_restore_mask();

=end

[nagachika (Tomoyuki Chikanaga)]

• Status changed from Open to Closed
• % Done changed from 0 to 100

=begin
This issue was solved with changeset r30657.
Tomoyuki, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

---

• vm_eval.c (rb_throw_obj): add GC guard to prevent intermediate
  variable from GC. [Bug #4322] [ruby-dev:43108]
  =end