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Null pointer dereference in Perl_pp_multiconcat #16468

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p5pRT opened this issue Mar 17, 2018 · 5 comments

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@p5pRT p5pRT commented Mar 17, 2018

Migrated from rt.perl.org#132991 (status was 'new')

Searchable as RT132991$

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@p5pRT p5pRT commented Mar 17, 2018

From jeremy@feusi.co

Created by jeremy@feusi.co

Reply-To​: jeremy@​feusi.co

This is a bug report for perl from jeremy@​feusi.co,
generated with the help of perlbug 1.40 running under perl 5.26.1.

-----------------------------------------------------------------
Perl segfaults when executing the attached program (perl <progname>) due to a null pointer dereference in Perl_pp_multiconcat.
This bug can also reproduced on archlinux and debian with standard installation configuration and version 5.26.1.

Detailed backtrace​:

ASAN​:DEADLYSIGNAL

==9327==ERROR​: AddressSanitizer​: SEGV on unknown address 0x00000000000c (pc 0x00000084e5f2 bp 0x7ffeed336030 sp 0x7ffeed335a40 T0)
==9327==The signal is caused by a READ memory access.
==9327==Hint​: address points to the zero page.
  #0 0x84e5f1 in Perl_pp_multiconcat /home/jfe/perl52/pp_hot.c
  #1 0x8488be in Perl_runops_standard /home/jfe/perl52/run.c​:41​:26
  #2 0xa95bf6 in S_regmatch /home/jfe/perl52/regexec.c​:7424​:3
  #3 0xa74ea0 in S_regtry /home/jfe/perl52/regexec.c​:4086​:14
  #4 0xa57204 in Perl_regexec_flags /home/jfe/perl52/regexec.c​:3943​:7
  #5 0x877ab1 in Perl_pp_subst /home/jfe/perl52/pp_hot.c​:4212​:10
  #6 0x8488be in Perl_runops_standard /home/jfe/perl52/run.c​:41​:26
  #7 0x5dbc91 in S_run_body /home/jfe/perl52/perl.c
  #8 0x5dabb4 in perl_run /home/jfe/perl52/perl.c​:2646​:2
  #9 0x52f0b8 in main /home/jfe/perl52/perlmain.c​:122​:9
  #10 0x7fe328886f29 in __libc_start_main (/lib/x86_64-linux-gnu/libc.so.6+0x20f29)
  #11 0x43f999 in _start (/home/jfe/perl52/perl+0x43f999)

AddressSanitizer can not provide additional info.
SUMMARY​: AddressSanitizer​: SEGV /home/jfe/perl52/pp_hot.c in Perl_pp_multiconcat
==9327==ABORTING

This bug was found with honggfuzz and asan.

Perl Info

Flags:
    category=core
    severity=high

Site configuration information for perl 5.26.1:

Configured by Debian at Fri Jan 12 19:31:09 UTC 2018.

Summary of my perl5 (revision 5 version 26 subversion 1) configuration:
   
  Platform:
    osname=linux
    osvers=4.9.0
    archname=x86_64-linux-gnu-thread-multi
    uname='linux localhost 4.9.0 #1 smp debian 4.9.0 x86_64 gnulinux '
    config_args='-Dusethreads -Duselargefiles -Dcc=x86_64-linux-gnu-gcc -Dcpp=x86_64-linux-gnu-cpp -Dld=x86_64-linux-gnu-gcc -Dccflags=-DDEBIAN -Wdate-time -D_FORTIFY_SOURCE=2 -g -O2 -fdebug-prefix-map=/build/perl-awpeXx/perl-5.26.1=. -fstack-protector-strong -Wformat -Werror=format-security -Dldflags= -Wl,-z,relro -Dlddlflags=-shared -Wl,-z,relro -Dcccdlflags=-fPIC -Darchname=x86_64-linux-gnu -Dprefix=/usr -Dprivlib=/usr/share/perl/5.26 -Darchlib=/usr/lib/x86_64-linux-gnu/perl/5.26 -Dvendorprefix=/usr -Dvendorlib=/usr/share/perl5 -Dvendorarch=/usr/lib/x86_64-linux-gnu/perl5/5.26 -Dsiteprefix=/usr/local -Dsitelib=/usr/local/share/perl/5.26.1 -Dsitearch=/usr/local/lib/x86_64-linux-gnu/perl/5.26.1 -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 -Ui_xlocale -Uversiononly -DDEBUGGING=-g -Doptimize=-O2 -dEs -Duseshrplib -Dlibperl=libperl.so.5.26.1'
    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='x86_64-linux-gnu-gcc'
    ccflags ='-D_REENTRANT -D_GNU_SOURCE -DDEBIAN -fwrapv -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 -fwrapv -fno-strict-aliasing -pipe -I/usr/local/include'
    ccversion=''
    gccversion='7.2.0'
    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='x86_64-linux-gnu-gcc'
    ldflags =' -fstack-protector-strong -L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib/gcc/x86_64-linux-gnu/7/include-fixed /usr/include/x86_64-linux-gnu /usr/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib
    libs=-lgdbm -lgdbm_compat -ldb -ldl -lm -lpthread -lc -lcrypt
    perllibs=-ldl -lm -lpthread -lc -lcrypt
    libc=libc-2.26.so
    so=so
    useshrplib=true
    libperl=libperl.so.5.26
    gnulibc_version='2.26'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs
    dlext=so
    d_dlsymun=undef
    ccdlflags='-Wl,-E'
    cccdlflags='-fPIC'
    lddlflags='-shared -L/usr/local/lib -fstack-protector-strong'

Locally applied patches:
    DEBPKG:debian/cpan_definstalldirs - Provide a sensible INSTALLDIRS default for modules installed from CPAN.
    DEBPKG:debian/db_file_ver - https://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 - https://bugs.debian.org/290336 Tweak enc2xs to follow symlinks and ignore missing @INC directories.
    DEBPKG:debian/errno_ver - https://bugs.debian.org/343351 Remove Errno version check due to upgrade problems with long-running processes.
    DEBPKG:debian/libperl_embed_doc - https://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 under /usr/lib
    DEBPKG:debian/no_packlist_perllocal - Don't install .packlist or perllocal.pod for perl or vendor
    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/perlivp - https://bugs.debian.org/510895 Make perlivp skip include directories in /usr/local
    DEBPKG:debian/deprecate-with-apt - https://bugs.debian.org/747628 Point users to Debian packages of deprecated core modules
    DEBPKG:debian/squelch-locale-warnings - https://bugs.debian.org/508764 Squelch locale warnings in Debian package maintainer scripts
    DEBPKG:debian/patchlevel - https://bugs.debian.org/567489 List packaged patches for 5.26.1-4 in patchlevel.h
    DEBPKG:fixes/document_makemaker_ccflags - https://bugs.debian.org/628522 [rt.cpan.org #68613] Document that CCFLAGS should include $Config{ccflags}
    DEBPKG:debian/find_html2text - https://bugs.debian.org/640479 Configure CPAN::Distribution with correct name of html2text
    DEBPKG:debian/perl5db-x-terminal-emulator.patch - https://bugs.debian.org/668490 Invoke x-terminal-emulator rather than xterm in perl5db.pl
    DEBPKG:debian/cpan-missing-site-dirs - https://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] https://bugs.debian.org/587650 Memoize::Storable: respect 'nstore' option not respected
    DEBPKG:debian/makemaker-pasthru - https://bugs.debian.org/758471 Pass LD settings through to subdirectories
    DEBPKG:debian/makemaker-manext - https://bugs.debian.org/247370 Make EU::MakeMaker honour MANnEXT settings in generated manpage headers
    DEBPKG:debian/kfreebsd-softupdates - https://bugs.debian.org/796798 Work around Debian Bug#796798
    DEBPKG:fixes/autodie-scope - https://bugs.debian.org/798096 Fix a scoping issue with "no autodie" and the "system" sub
    DEBPKG:fixes/memoize-pod - [rt.cpan.org #89441] Fix POD errors in Memoize
    DEBPKG:debian/hurd-softupdates - https://bugs.debian.org/822735 Fix t/op/stat.t failures on hurd
    DEBPKG:fixes/math_complex_doc_great_circle - https://bugs.debian.org/697567 [rt.cpan.org #114104] Math::Trig: clarify definition of great_circle_midpoint
    DEBPKG:fixes/math_complex_doc_see_also - https://bugs.debian.org/697568 [rt.cpan.org #114105] Math::Trig: add missing SEE ALSO
    DEBPKG:fixes/math_complex_doc_angle_units - https://bugs.debian.org/731505 [rt.cpan.org #114106] Math::Trig: document angle units
    DEBPKG:fixes/cpan_web_link - https://bugs.debian.org/367291 CPAN: Add link to main CPAN web site
    DEBPKG:fixes/time_piece_doc - https://bugs.debian.org/817925 Time::Piece: Improve documentation for add_months and add_years
    DEBPKG:fixes/extutils_makemaker_reproducible - https://bugs.debian.org/835815 https://bugs.debian.org/834190 Make perllocal.pod files reproducible
    DEBPKG:fixes/file_path_hurd_errno - File-Path: Fix test failure in Hurd due to hard-coded ENOENT
    DEBPKG:debian/hppa_op_optimize_workaround - https://bugs.debian.org/838613 Temporarily lower the optimization of op.c on hppa due to gcc-6 problems
    DEBPKG:debian/installman-utf8 - https://bugs.debian.org/840211 Generate man pages with UTF-8 characters
    DEBPKG:fixes/file_path_chmod_race - https://bugs.debian.org/863870 [rt.cpan.org #121951] Prevent directory chmod race attack.
    DEBPKG:fixes/extutils_file_path_compat - Correct the order of tests of chmod(). (#294)
    DEBPKG:fixes/getopt-long-2 - [rt.cpan.org #120300] Withdraw part of commit 5d9947fb445327c7299d8beb009d609bc70066c0, which tries to implement more GNU getopt_long campatibility. GNU
    DEBPKG:fixes/getopt-long-3 - provide a default value for optional arguments
    DEBPKG:fixes/getopt-long-4 - https://bugs.debian.org/864544 [rt.cpan.org #122068] Fix issue #122068.
    DEBPKG:fixes/test-builder-reset - https://bugs.debian.org/865894 Reset inside subtest maintains parent
    DEBPKG:debian/hppa_opmini_optimize_workaround - https://bugs.debian.org/869122 Lower the optimization level of opmini.c on hppa
    DEBPKG:debian/sh4_op_optimize_workaround - https://bugs.debian.org/869373 Also lower the optimization level of op.c and opmini.c on sh4
    DEBPKG:fixes/json-pp-example - [rt.cpan.org #92793] https://bugs.debian.org/871837 fix RT-92793: bug in SYNOPSIS
    DEBPKG:debian/perldoc-pager - https://bugs.debian.org/870340 [rt.cpan.org #120229] Fix perldoc terminal escapes when sensible-pager is less
    DEBPKG:debian/prune_libs - https://bugs.debian.org/128355 Prune the list of libraries wanted to what we actually need.
    DEBPKG:debian/configure-regen - https://bugs.debian.org/762638 Regenerate Configure et al. after probe unit changes
    DEBPKG:fixes/rename-filexp.U-phase1 - regen-configure: rename filexp.U to filexp_path.U, phase 1
    DEBPKG:fixes/rename-filexp.U-phase2 - regen-configure: rename filexp.U to filexp_path.U, phase 2
    DEBPKG:fixes/packaging_test_skips - Skip various tests if PERL_BUILD_PACKAGING is set
    DEBPKG:debian/mod_paths - Tweak @INC ordering for Debian
    DEBPKG:fixes/encode-alias-regexp - https://bugs.debian.org/880085 fix https://github.com/dankogai/p5-encode/issues/127


@INC for perl 5.26.1:
    /etc/perl
    /usr/local/lib/x86_64-linux-gnu/perl/5.26.1
    /usr/local/share/perl/5.26.1
    /usr/lib/x86_64-linux-gnu/perl5/5.26
    /usr/share/perl5
    /usr/lib/x86_64-linux-gnu/perl/5.26
    /usr/share/perl/5.26
    /usr/local/lib/site_perl
    /usr/lib/x86_64-linux-gnu/perl-base


Environment for perl 5.26.1:
    HOME=/home/jfe
    LANG=en_US.UTF-8
    LANGUAGE=en_US.UTF-8
    LC_ADDRESS=de_CH.UTF-8
    LC_ALL=en_US.UTF-8
    LC_COLLATE=de_CH.UTF-8
    LC_IDENTIFICATION=de_CH.UTF-8
    LC_MEASUREMENT=de_CH.UTF-8
    LC_MESSAGES=en_US.UTF-8
    LC_MONETARY=de_CH.UTF-8
    LC_NAME=de_CH.UTF-8
    LC_NUMERIC=de_CH.UTF-8
    LC_PAPER=de_CH.UTF-8
    LC_TELEPHONE=de_CH.UTF-8
    LC_TIME=en_DK.UTF-8
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/jfe/.cargo/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games
    PERL_BADLANG (unset)
    SHELL=/bin/bash

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@p5pRT p5pRT commented Mar 17, 2018

From jeremy@feusi.co

#!./perl
m/(?{print <<EOF
A$A
EOF
})/g;
eval 's/${\%A}{3}//e';

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@richardleach richardleach commented Oct 24, 2019

Looks like this has been fixed:

This is perl 5, version 30, subversion 0 (v5.30.0) built for MSWin32-x64-multi-thread
C:\fldr>perl fzz.pl
A
A
A
This is perl 5, version 28, subversion 1 (v5.28.1) built for x86_64-linux-gnu-thread-multi
me@disbox:~# perl fzz.pl 
A
A
A

Ran out of time to dig deeper or bisect. Can do so at the weekend, unless someone wants to beat me to it.

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@richardleach richardleach commented Oct 26, 2019

Looks like it was fixed by 4e521aa

commit 4e521aaf3ed717774455b3906bd5aa46bc397319
Author: David Mitchell <davem@iabyn.com>
Date:   Tue Feb 5 13:48:21 2019 +0000

    Avoid leak in multiconcat with overloading.

    RT #133789

    In the path taken through pp_multiconcat() when one or more args have
    side-effects such tieing or overloading, multiconcat has to decide
    whether to just return the result of all the concatting as-is, or to
    first assign it to an expression or variable if the op includes an
    implicit assign (such as $lex = x.y.z or $a[0] = x.y.z).

    The code was getting this right for those two cases, and was also
    getting it right for the append cases ($lex .= x.y.z and $a[0] .= x.y.z),
    which don't need assigns. But for the bare case (x.y.z) it was assigning
    to the op's targ as well as returning the value. Hence leaking a
    reference until destruction of the sub and its pad.

    This commit stops the assign in that last case.
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@atoomic atoomic commented Oct 28, 2019

the first release for 4e521aa is v5.29.8

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