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[perl #129059] lexical subs - my sub using our sub segfaults

From:
Matthew Horsfall
Date:
August 23, 2016 17:59
Subject:
[perl #129059] lexical subs - my sub using our sub segfaults
Message ID:
rt-4.0.24-20928-1471975164-1445.129059-75-0@perl.org
# New Ticket Created by  Matthew Horsfall 
# Please include the string:  [perl #129059]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=129059 >


This is a bug report for perl from wolfsage@gmail.com,
generated with the help of perlbug 1.39 running under perl 5.18.2.


-----------------------------------------------------------------
[Please describe your issue here]

$ cat uh.pl

  use v5.24.0;
  use experimental qw(lexical_subs);

  our sub speak { }

  # Crashes with or without the package decl
  # package Cat {
    my sub meow {
      speak();
    }
  #}

$ gdb --args ./perl -Ilib uh.pl

  [...]
  (gdb) run
  Starting program: /home/mhorsfall/p5/perl/perl -Ilib uh.pl
  [Thread debugging using libthread_db enabled]
  Using host libthread_db library "/lib/x86_64-linux-gnu/libthread_db.so.1".

  Program received signal SIGSEGV, Segmentation fault.
  0x000000000048c4f5 in Perl_cv_undef_flags (cv=0x87ba40, flags=0) at pad.c:413
  413                U32 inner_rc = SvREFCNT(innercv);
  (gdb) bt
  #0  0x000000000048c4f5 in Perl_cv_undef_flags (cv=0x87ba40, flags=0)
      at pad.c:413
  #1  0x000000000048bf29 in Perl_cv_undef (cv=0x87ba40) at pad.c:302
  #2  0x000000000055563b in Perl_leave_scope (base=0) at scope.c:1194
  #3  0x000000000055e48e in Perl_pp_leave () at pp_ctl.c:2090
  #4  0x00000000005051a2 in Perl_runops_standard () at run.c:41
  #5  0x000000000044916f in S_run_body (oldscope=1) at perl.c:2525
  #6  0x0000000000448d2c in perl_run (my_perl=0x856010) at perl.c:2448
  #7  0x000000000041edc5 in main (argc=3, argv=0x7fffffffe138,
      env=0x7fffffffe158) at perlmain.c:123
  (gdb) p innercv
  $1 = (CV * const) 0x0

[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=low
---
Site configuration information for perl 5.18.2:

Configured by Debian Project at Tue Mar  1 17:12:59 UTC 2016.

Summary of my perl5 (revision 5 version 18 subversion 2) configuration:

  Platform:
    osname=linux, osvers=3.13.0-79-generic,
archname=x86_64-linux-gnu-thread-multi
    uname='linux lgw01-37 3.13.0-79-generic #123-ubuntu smp fri feb 19
14:27:58 utc 2016 x86_64 x86_64 x86_64 gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dccflags=-DDEBIAN
-D_FORTIFY_SOURCE=2 -g -O2 -fstack-protector --param=ssp-buffer-size=4
-Wformat -Werror=format-security -Dldflags= -Wl,-Bsymbolic-functions
-Wl,-z,relro -Dlddlflags=-shared -Wl,-Bsymbolic-functions -Wl,-z,relro
-Dcccdlflags=-fPIC -Darchname=x86_64-linux-gnu -Dprefix=/usr
-Dprivlib=/usr/share/perl/5.18 -Darchlib=/usr/lib/perl/5.18
-Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5
-Dvendorarch=/usr/lib/perl5 -Dsiteprefix=/usr/local
-Dsitelib=/usr/local/share/perl/5.18.2
-Dsitearch=/usr/local/lib/perl/5.18.2 -Dman1dir=/usr/share/man/man1
-Dman3dir=/usr/share/man/man3 -Dsiteman1dir=/usr/local/man/man1
-Dsiteman3dir=/usr/local/man/man3 -Duse64bitint -Dman1ext=1
-Dman3ext=3perl -Dpager=/usr/bin/sensible-pager -Uafs -Ud_csh
-Ud_ualarm -Uusesfio -Uusenm -Ui_libutil -Uversiononly -DDEBUGGING=-g
-Doptimize=-O2 -Duseshrplib -Dlibperl=libperl.so.5.18.2 -des'
    hint=recommended, useposix=true, d_sigaction=define
    useithreads=define, usemultiplicity=define
    useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
    use64bitint=define, use64bitall=define, uselongdouble=undef
    usemymalloc=n, bincompat5005=undef
  Compiler:
    cc='cc', ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN
-fstack-protector -fno-strict-aliasing -pipe -I/usr/local/include
-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
    optimize='-O2 -g',
    cppflags='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fstack-protector
-fno-strict-aliasing -pipe -I/usr/local/include'
    ccversion='', gccversion='4.8.2', gccosandvers=''
    intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
    d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
    ivtype='long', ivsize=8, nvtype='double', nvsize=8, Off_t='off_t',
lseeksize=8
    alignbytes=8, prototype=define
  Linker and Libraries:
    ld='cc', ldflags =' -fstack-protector -L/usr/local/lib'
    libpth=/usr/local/lib /lib/x86_64-linux-gnu /lib/../lib
/usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib /usr/lib
    libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
    perllibs=-ldl -lm -lpthread -lc -lcrypt
    libc=, so=so, useshrplib=true, libperl=libperl.so.5.18.2
    gnulibc_version='2.19'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
    cccdlflags='-fPIC', lddlflags='-shared -L/usr/local/lib -fstack-protector'

Locally applied patches:
    DEBPKG:debian/cpan_definstalldirs - Provide a sensible INSTALLDIRS
default for modules installed from CPAN.
    DEBPKG:debian/db_file_ver - http://bugs.debian.org/340047 Remove
overly restrictive DB_File version check.
    DEBPKG:debian/doc_info - Replace generic man(1) instructions with
Debian-specific information.
    DEBPKG:debian/enc2xs_inc - http://bugs.debian.org/290336 Tweak
enc2xs to follow symlinks and ignore missing @INC directories.
    DEBPKG:debian/errno_ver - http://bugs.debian.org/343351 Remove
Errno version check due to upgrade problems with long-running
processes.
    DEBPKG:debian/libperl_embed_doc - http://bugs.debian.org/186778
Note that libperl-dev package is required for embedded linking
    DEBPKG:fixes/respect_umask - Respect umask during installation
    DEBPKG:debian/writable_site_dirs - Set umask approproately for
site install directories
    DEBPKG:debian/extutils_set_libperl_path - EU:MM: Set location of
libperl.a to /usr/lib
    DEBPKG:debian/no_packlist_perllocal - Don't install .packlist or
perllocal.pod for perl or vendor
    DEBPKG:debian/prefix_changes - Fiddle with *PREFIX and variables
written to the makefile
    DEBPKG:debian/fakeroot - Postpone LD_LIBRARY_PATH evaluation to
the binary targets.
    DEBPKG:debian/instmodsh_doc - Debian policy doesn't install
.packlist files for core or vendor.
    DEBPKG:debian/ld_run_path - Remove standard libs from LD_RUN_PATH
as per Debian policy.
    DEBPKG:debian/libnet_config_path - Set location of libnet.cfg to
/etc/perl/Net as /usr may not be writable.
    DEBPKG:debian/mod_paths - Tweak @INC ordering for Debian
    DEBPKG:debian/module_build_man_extensions -
http://bugs.debian.org/479460 Adjust Module::Build manual page
extensions for the Debian Perl policy
    DEBPKG:debian/prune_libs - http://bugs.debian.org/128355 Prune the
list of libraries wanted to what we actually need.
    DEBPKG:fixes/net_smtp_docs - [rt.cpan.org #36038]
http://bugs.debian.org/100195 Document the Net::SMTP 'Port' option
    DEBPKG:debian/perlivp - http://bugs.debian.org/510895 Make perlivp
skip include directories in /usr/local
    DEBPKG:debian/cpanplus_definstalldirs -
http://bugs.debian.org/533707 Configure CPANPLUS to use the site
directories by default.
    DEBPKG:debian/cpanplus_config_path - Save local versions of
CPANPLUS::Config::System into /etc/perl.
    DEBPKG:debian/deprecate-with-apt - http://bugs.debian.org/702096
Point users to Debian packages of deprecated core modules
    DEBPKG:debian/squelch-locale-warnings -
http://bugs.debian.org/508764 Squelch locale warnings in Debian
package maintainer scripts
    DEBPKG:debian/skip-upstream-git-tests - Skip tests specific to the
upstream Git repository
    DEBPKG:debian/patchlevel - http://bugs.debian.org/567489 List
packaged patches for 5.18.2-2ubuntu1.1 in patchlevel.h
    DEBPKG:debian/skip-kfreebsd-crash - http://bugs.debian.org/628493
[perl #96272] Skip a crashing test case in t/op/threads.t on
GNU/kFreeBSD
    DEBPKG:fixes/document_makemaker_ccflags -
http://bugs.debian.org/628522 [rt.cpan.org #68613] Document that
CCFLAGS should include $Config{ccflags}
    DEBPKG:debian/find_html2text - http://bugs.debian.org/640479
Configure CPAN::Distribution with correct name of html2text
    DEBPKG:debian/hurd_test_skip_stack - http://bugs.debian.org/650175
Disable failing GNU/Hurd tests dist/threads/t/stack.t
    DEBPKG:fixes/manpage_name_Test-Harness -
http://bugs.debian.org/650451 [rt.cpan.org #73399] cpan/Test-Harness:
add NAME headings in modules with POD
    DEBPKG:debian/makemaker-pasthru - http://bugs.debian.org/660195
[rt.cpan.org #28632] Make EU::MM pass LD through to recursive
Makefile.PL invocations
    DEBPKG:debian/perl5db-x-terminal-emulator.patch -
http://bugs.debian.org/668490 Invoke x-terminal-emulator rather than
xterm in perl5db.pl
    DEBPKG:debian/cpan-missing-site-dirs -
http://bugs.debian.org/688842 Fix CPAN::FirstTime defaults with
nonexisting site dirs if a parent is writable
    DEBPKG:fixes/memoize_storable_nstore - [rt.cpan.org #77790]
http://bugs.debian.org/587650 Memoize::Storable: respect 'nstore'
option not respected
    DEBPKG:fixes/net_ftp_failed_command - [rt.cpan.org #37700]
http://bugs.debian.org/491062 Net::FTP: cope gracefully with a failed
command
    DEBPKG:fixes/perlbug-patchlist - [3541c11]
http://bugs.debian.org/710842 [perl #118433] Make perlbug look up the
list of local patches at run time
    DEBPKG:fixes/module_metadata_security_doc - [68cdd4b]
CVE-2013-1437 documentation fix
    DEBPKG:fixes/module_metadata_taint_fix - [bff978f]
http://bugs.debian.org/722210 [rt.cpan.org #88576] untaint version, if
needed, in Module::Metadata
    DEBPKG:fixes/IPC-SysV-spelling - http://bugs.debian.org/730558
[rt.cpan.org #86736] Fix spelling of IPC_CREAT in IPC-SysV
documentation
    DEBPKG:fixes/fix-undef-source -
    DEBPKG:fixes/CVE-2013-7422.patch - [PATCH] [perl #119505] Segfault
from bad backreference
    DEBPKG:fixes/CVE-2014-4330.patch - [PATCH] don't recurse
infinitely in Data::Dumper
    DEBPKG:fixes/CVE-2016-2381.patch - [PATCH 1/2] remove duplicate
environment variables from environ

---
@INC for perl 5.18.2:
    /etc/perl
    /usr/local/lib/perl/5.18.2
    /usr/local/share/perl/5.18.2
    /usr/lib/perl5
    /usr/share/perl5
    /usr/lib/perl/5.18
    /usr/share/perl/5.18
    /usr/local/lib/site_perl
    .

---
Environment for perl 5.18.2:
    HOME=/home/mhorsfall
    LANG=en_US.UTF-8
    LANGUAGE=en_US
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/mhorsfall/.plenv/libexec:/home/mhorsfall/.plenv/plugins/perl-build/bin:/home/mhorsfall/.plenv/shims:/home/mhorsfall/.plenv/bin:/home/mhorsfall/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games
    PERLDOC=-oman
    PERL_BADLANG (unset)
    SHELL=/bin/bash




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