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[perl #131929] multi-arg open() error leaks

From:
Zefram
Date:
August 19, 2017 03:08
Subject:
[perl #131929] multi-arg open() error leaks
Message ID:
rt-4.0.24-1817-1503112078-1250.131929-75-0@perl.org
# New Ticket Created by  Zefram 
# Please include the string:  [perl #131929]
# in the subject line of all future correspondence about this issue. 
# <URL: https://rt.perl.org/Ticket/Display.html?id=131929 >



This is a bug report for perl from zefram@fysh.org,
generated with the help of perlbug 1.40 running under perl 5.27.2.


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

If an open() operation specifies a list of layers, and has more than one
argument, and the layer handling the opening can't accept more than one
argument, then the operation leaks:

$ perl -lwe 'for(0..2) { system("ps u $$"); for(0..9999) { eval { open($f, ">:scalar", \$a, 2) } } }'
Name "main::f" used only once: possible typo at -e line 1.
USER	   PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
zefram	 10526	0.0  0.0  22268  3268 pts/3    S+   03:59   0:00 perl -lwe for(0
USER	   PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
zefram	 10526	0.0  0.0  26308  6076 pts/3    S+   03:59   0:00 perl -lwe for(0
USER	   PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
zefram	 10526	0.0  0.0  28156  7964 pts/3    S+   03:59   0:00 perl -lwe for(0

The problem is that the argument count error is signalled as an exception
(unlike most opening errors) but explicit freeing of the layer list is
required (in PerlIO_openn()).  I'm not sure which part of this is the
bug: perhaps the error ought to be signalled through errno, or perhaps
the code branch that croaks should explicitly free the layer list, or
perhaps the operation should be made robust against all exceptions by
using some arrangement like mortalisation to free the layer list.

[Please do not change anything below this line]
-----------------------------------------------------------------
---
Flags:
    category=core
    severity=low
---
Site configuration information for perl 5.27.2:

Configured by zefram at Thu Jul 20 23:32:33 BST 2017.

Summary of my perl5 (revision 5 version 27 subversion 2) configuration:
   
  Platform:
    osname=linux
    osvers=3.16.0-4-amd64
    archname=x86_64-linux-thread-multi
    uname='linux barba.rous.org 3.16.0-4-amd64 #1 smp debian 3.16.43-2+deb8u2 (2017-06-26) x86_64 gnulinux '
    config_args='-des -Dprefix=/home/zefram/usr/perl/perl_install/perl-5.27.2-i64-f52 -Duselargefiles -Dusethreads -Uafs -Ud_csh -Uusesfio -Uusenm -Duseshrplib -Dusedevel -Uversiononly -Ui_db'
    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='-O2'
    cppflags='-D_REENTRANT -D_GNU_SOURCE -fwrapv -fno-strict-aliasing -pipe -fstack-protector-strong -I/usr/local/include'
    ccversion=''
    gccversion='4.9.2'
    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 =' -fstack-protector-strong -L/usr/local/lib'
    libpth=/usr/local/lib /usr/lib/gcc/x86_64-linux-gnu/4.9/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=-lpthread -lnsl -ldb -ldl -lm -lcrypt -lutil -lc
    perllibs=-lpthread -lnsl -ldl -lm -lcrypt -lutil -lc
    libc=libc-2.19.so
    so=so
    useshrplib=true
    libperl=libperl.so
    gnulibc_version='2.19'
  Dynamic Linking:
    dlsrc=dl_dlopen.xs
    dlext=so
    d_dlsymun=undef
    ccdlflags='-Wl,-E -Wl,-rpath,/home/zefram/usr/perl/perl_install/perl-5.27.2-i64-f52/lib/5.27.2/x86_64-linux-thread-multi/CORE'
    cccdlflags='-fPIC'
    lddlflags='-shared -O2 -L/usr/local/lib -fstack-protector-strong'


---
@INC for perl 5.27.2:
    /home/zefram/usr/perl/perl_install/perl-5.27.2-i64-f52/lib/site_perl/5.27.2/x86_64-linux-thread-multi
    /home/zefram/usr/perl/perl_install/perl-5.27.2-i64-f52/lib/site_perl/5.27.2
    /home/zefram/usr/perl/perl_install/perl-5.27.2-i64-f52/lib/5.27.2/x86_64-linux-thread-multi
    /home/zefram/usr/perl/perl_install/perl-5.27.2-i64-f52/lib/5.27.2

---
Environment for perl 5.27.2:
    HOME=/home/zefram
    LANG (unset)
    LANGUAGE (unset)
    LD_LIBRARY_PATH (unset)
    LOGDIR (unset)
    PATH=/home/zefram/usr/perl/perl_install/perl-5.27.2-i64-f52/bin:/home/zefram/usr/perl/util:/home/zefram/pub/x86_64-unknown-linux-gnu/bin:/home/zefram/pub/common/bin:/usr/bin:/bin:/usr/local/bin:/usr/games
    PERLDOC=-oman
    PERL_BADLANG (unset)
    SHELL=/usr/bin/zsh




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