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B module use freed sv #16539

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p5pRT opened this issue Apr 28, 2018 · 7 comments
Closed

B module use freed sv #16539

p5pRT opened this issue Apr 28, 2018 · 7 comments
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type-library

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@p5pRT
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p5pRT commented Apr 28, 2018

Migrated from rt.perl.org#133159 (status was 'rejected')

Searchable as RT133159$
@p5pRT
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p5pRT commented Apr 28, 2018

From damien-43@gmx.fr

Created by damien-43@gmx.fr

Hi
B module does not work with constants sv if it is created in eval 'string'.

% cat t.pl
use v5.26;
use B;

eval '
  $_ = B​::svref_2object(\"foo");
  p($_);
';
say "=" x 80;

p($_);

sub p {
  my $pv = shift;
  printf "PVX = '%s'\n", $pv->PVX;
  printf "CUR = %d\n", $_->CUR;
  printf "LEN = %d\n", $pv->LEN;
  printf "FLAGS = %d\n", $pv->FLAGS;
  printf "SvTYPE = %d\n", $pv->SvTYPE;
  say ref $pv->object_2svref;
}

% perl t.pl
PVX = 'foo'
CUR = 3
LEN = 10
FLAGS = 402736131
SvTYPE = 3
SCALAR

PVX = '��V�U'
CUR = 0
LEN = 94516509793920
FLAGS = 255
SvTYPE = 255
UNKNOWN
[1] 17092 segmentation fault (core dumped) perl t.pl

Perl Info 

Flags:
    category=library
    severity=low
    module=B

Site configuration information for perl 5.26.2:

Configured by builduser at Wed Apr 18 22:20:25 CEST 2018.

Summary of my perl5 (revision 5 version 26 subversion 2) configuration:
   
  Platform:
    osname=linux
    osvers=4.15.15-1-arch
    archname=x86_64-linux-thread-multi
    uname='linux flo-64 4.15.15-1-arch #1 smp preempt sat mar 31 23:59:25 utc 2018 x86_64 gnulinux '
    config_args='-des -Dusethreads -Duseshrplib -Doptimize=-march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong -fno-plt -Dprefix=/usr -Dvendorprefix=/usr -Dprivlib=/usr/share/perl5/core_perl -Darchlib=/usr/lib/perl5/5.26/core_perl -Dsitelib=/usr/share/perl5/site_perl -Dsitearch=/usr/lib/perl5/5.26/site_perl -Dvendorlib=/usr/share/perl5/vendor_perl -Dvendorarch=/usr/lib/perl5/5.26/vendor_perl -Dscriptdir=/usr/bin/core_perl -Dsitescript=/usr/bin/site_perl -Dvendorscript=/usr/bin/vendor_perl -Dinc_version_list=none -Dman1ext=1perl -Dman3ext=3perl -Dcccdlflags='-fPIC' -Dlddlflags=-shared -Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now -Dldflags=-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now'
    hint=recommended
    useposix=true
    d_sigaction=define
    useithreads=define
    usemultiplicity=define
    use64bitint=define
    use64bitall=define
    uselongdouble=undef
    usemymalloc=n
    default_inc_excludes_dot=define
    bincompat5005=undef
  Compiler:
    cc='cc'
    ccflags ='-D_REENTRANT -D_GNU_SOURCE -fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -D_FORTIFY_SOURCE=2'
    optimize='-march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong -fno-plt'
    cppflags='-D_REENTRANT -D_GNU_SOURCE -fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include'
    ccversion=''
    gccversion='7.3.1 20180312'
    gccosandvers=''
    intsize=4
    longsize=8
    ptrsize=8
    doublesize=8
    byteorder=12345678
    doublekind=3
    d_longlong=define
    longlongsize=8
    d_longdbl=define
    longdblsize=16
    longdblkind=3
    ivtype='long'
    ivsize=8
    nvtype='double'
    nvsize=8
    Off_t='off_t'
    lseeksize=8
    alignbytes=8
    prototype=define
  Linker and Libraries:
    ld='cc'
    ldflags ='-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now -fstack-protector-strong -L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib/gcc/x86_64-pc-linux-gnu/7.3.1/include-fixed /usr/lib /lib/../lib /usr/lib/../lib /lib /lib64 /usr/lib64
    libs=-lpthread -lnsl -lgdbm -ldb -ldl -lm -lcrypt -lutil -lc -lgdbm_compat
    perllibs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc
    libc=libc-2.26.so
    so=so
    useshrplib=true
    libperl=libperl.so
    gnulibc_version='2.26'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs
    dlext=so
    d_dlsymun=undef
    ccdlflags='-Wl,-E -Wl,-rpath,/usr/lib/perl5/5.26/core_perl/CORE'
    cccdlflags='-fPIC'
    lddlflags='-shared -Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now -L/usr/local/lib -fstack-protector-strong'



@INC for perl 5.26.2:
    /home/damien/.local/lib/perl5/x86_64-linux-thread-multi
    /home/damien/.local/lib/perl5
    /usr/lib/perl5/5.26/site_perl
    /usr/share/perl5/site_perl
    /usr/lib/perl5/5.26/vendor_perl
    /usr/share/perl5/vendor_perl
    /usr/lib/perl5/5.26/core_perl
    /usr/share/perl5/core_perl


Environment for perl 5.26.2:
    HOME=/home/damien
    LANG=fr_FR.UTF-8
    LANGUAGE (unset)
    LC_MESSAGES=
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/damien/.local/bin:/usr/local/sbin:/usr/local/bin:/usr/bin:/usr/lib/jvm/default/bin:/usr/bin/site_perl:/usr/bin/vendor_perl:/usr/bin/core_perl
    PERL5LIB=/home/damien/.local/lib/perl5
    PERL_BADLANG (unset)
    PERL_MB_OPT=--install_base "/home/damien/.local"
    PERL_MM_OPT=INSTALL_BASE=/home/damien/.local
    SHELL=/usr/bin/zsh

@p5pRT
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p5pRT commented May 7, 2018

From @jkeenan

On Sat, 28 Apr 2018 17​:53​:50 GMT, damien-43@​gmx.fr wrote​:

This is a bug report for perl from damien-43@​gmx.fr,
generated with the help of perlbug 1.40 running under perl 5.26.2.

-----------------------------------------------------------------
[Please describe your issue here]
Hi
B module does not work with constants sv if it is created in eval
'string'.

% cat t.pl
use v5.26;
use B;

eval '
$_ = B​::svref_2object(\"foo");
p($_);
';
say "=" x 80;

p($_);

sub p {
my $pv = shift;
printf "PVX = '%s'\n", $pv->PVX;
printf "CUR = %d\n", $_->CUR;
printf "LEN = %d\n", $pv->LEN;
printf "FLAGS = %d\n", $pv->FLAGS;
printf "SvTYPE = %d\n", $pv->SvTYPE;
say ref $pv->object_2svref;
}

% perl t.pl
PVX = 'foo'
CUR = 3
LEN = 10
FLAGS = 402736131
SvTYPE = 3
SCALAR

PVX = '��V�U'
CUR = 0
LEN = 94516509793920
FLAGS = 255
SvTYPE = 255
UNKNOWN
[1] 17092 segmentation fault (core dumped) perl t.pl

[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags​:
category=library
severity=low
module=B
---
Site configuration information for perl 5.26.2​:

I've been able to replicate this in 5.20.3 and 5.24.1. Hence, it was not introduced in the 5.27 development cycle and is not a blocker for 5.28.0.

Thank you very much.
--
James E Keenan (jkeenan@​cpan.org)

@p5pRT
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p5pRT commented May 7, 2018

The RT System itself - Status changed from 'new' to 'open'

@p5pRT
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p5pRT commented May 13, 2018

From damien-43@gmx.fr

Hi
A another related bug with constants in eval "string"

$ perl -MB -E '(eval q< B​::svref_2object(\*foo) >)->NAME'
[1] 5393 segmentation fault (core dumped) perl ...

@p5pRT
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p5pRT commented May 29, 2018

From damien-43@gmx.fr

I am realizing which B.pm doesn't refcount the reference.
Sorry for the noise...

This ticket should be closed.

Perhaps, some warnings should be added in top of B documentation to
avoid future mistake?

Thanks!

@p5pRT
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p5pRT commented May 29, 2018

From @jkeenan

On Tue, 29 May 2018 08​:53​:51 GMT, damien-43@​gmx.fr wrote​:

I am realizing which B.pm doesn't refcount the reference.
Sorry for the noise...

This ticket should be closed.

Perhaps, some warnings should be added in top of B documentation to
avoid future mistake?

Thanks!

Closing per request from original poster.
--
James E Keenan (jkeenan@​cpan.org)

@p5pRT
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p5pRT commented May 29, 2018

@jkeenan - Status changed from 'open' to 'rejected'

@p5pRT p5pRT closed this as completed May 29, 2018
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