Ubuntu Manpage: perl5241delta - what is new for perl v5.24.1

Provided by: perl-doc_5.26.1-6ubuntu0.7_all

NAME

       perl5241delta - what is new for perl v5.24.1

DESCRIPTION

       This document describes differences between the 5.24.0 release and the 5.24.1 release.

       If you are upgrading from an earlier release such as 5.22.0, first read perl5240delta, which describes
       differences between 5.22.0 and 5.24.0.

Security

-Di switch is now required for PerlIO debugging output
Previously PerlIO debugging output would be sent to the file specified by the "PERLIO_DEBUG" environment
variable if perl wasn't running setuid and the -T or -t switches hadn't been parsed yet.

If perl performed output at a point where it hadn't yet parsed its switches this could result in perl
creating or overwriting the file named by "PERLIO_DEBUG" even when the -T switch had been supplied.

Perl now requires the -Di switch to produce PerlIO debugging output. By default this is written to
"stderr", but can optionally be redirected to a file by setting the "PERLIO_DEBUG" environment variable.

If perl is running setuid or the -T switch was supplied "PERLIO_DEBUG" is ignored and the debugging
output is sent to "stderr" as for any other -D switch.

Core modules and tools no longer search "." for optional modules
The tools and many modules supplied in core no longer search the default current directory entry in @INC
for optional modules. For example, Storable will remove the final "." from @INC before trying to load
Log::Agent.

This prevents an attacker injecting an optional module into a process run by another user where the
current directory is writable by the attacker, e.g. the /tmp directory.

In most cases this removal should not cause problems, but difficulties were encountered with base, which
treats every module name supplied as optional. These difficulties have not yet been resolved, so for
this release there are no changes to base. We hope to have a fix for base in Perl 5.24.2.

To protect your own code from this attack, either remove the default "." entry from @INC at the start of
your script, so:

#!/usr/bin/perl
use strict;
...

becomes:

#!/usr/bin/perl
BEGIN { pop @INC if $INC[-1] eq '.' }
use strict;
...

or for modules, remove "." from a localized @INC, so:

my $can_foo = eval { require Foo; }

becomes:

my $can_foo = eval {
local @INC = @INC;
pop @INC if $INC[-1] eq '.';
require Foo;
};

Incompatible Changes

       Other than the security changes above there are no changes intentionally incompatible with Perl 5.24.0.
       If any exist, they are bugs, and we request that you submit a report.  See "Reporting Bugs" below.

Modules and Pragmata

Updated Modules and Pragmata
• Archive::Tar has been upgraded from version 2.04 to 2.04_01.

• bignum has been upgraded from version 0.42 to 0.42_01.

• CPAN has been upgraded from version 2.11 to 2.11_01.

• Digest has been upgraded from version 1.17 to 1.17_01.

• Digest::SHA has been upgraded from version 5.95 to 5.95_01.

• Encode has been upgraded from version 2.80 to 2.80_01.

• ExtUtils::MakeMaker has been upgraded from version 7.10_01 to 7.10_02.

• File::Fetch has been upgraded from version 0.48 to 0.48_01.

• File::Spec has been upgraded from version 3.63 to 3.63_01.

• HTTP::Tiny has been upgraded from version 0.056 to 0.056_001.

• IO has been upgraded from version 1.36 to 1.36_01.

• The IO-Compress modules have been upgraded from version 2.069 to 2.069_001.

• IPC::Cmd has been upgraded from version 0.92 to 0.92_01.

• JSON::PP has been upgraded from version 2.27300 to 2.27300_01.

• Locale::Maketext has been upgraded from version 1.26 to 1.26_01.

• Locale::Maketext::Simple has been upgraded from version 0.21 to 0.21_01.

• Memoize has been upgraded from version 1.03 to 1.03_01.

• Module::CoreList has been upgraded from version 5.20160506 to 5.20170114_24.

• Net::Ping has been upgraded from version 2.43 to 2.43_01.

• Parse::CPAN::Meta has been upgraded from version 1.4417 to 1.4417_001.

• Pod::Html has been upgraded from version 1.22 to 1.2201.

• Pod::Perldoc has been upgraded from version 3.25_02 to 3.25_03.

• Storable has been upgraded from version 2.56 to 2.56_01.

• Sys::Syslog has been upgraded from version 0.33 to 0.33_01.

• Test has been upgraded from version 1.28 to 1.28_01.

• Test::Harness has been upgraded from version 3.36 to 3.36_01.

• XSLoader has been upgraded from version 0.21 to 0.22, fixing a security hole in which binary files
could be loaded from a path outside of @INC. [perl #128528]
<https://rt.perl.org/Public/Bug/Display.html?id=128528>

Documentation

   Changes to Existing Documentation
       perlapio

       •   The documentation of "PERLIO_DEBUG" has been updated.

       perlrun

       •   The new -Di switch has been documented, and the documentation of "PERLIO_DEBUG" has been updated.

Testing

       •   A  new  test  script,  t/run/switchDx.t,  has  been  added to test that the new -Di switch is working
           correctly.

Selected Bug Fixes

       •   The change to hashbang redirection introduced in Perl 5.24.0, whereby perl would redirect to  another
           interpreter  (Perl  6)  if  it  found a hashbang path which contains "perl" followed by "6", has been
           reverted because it broke in cases such as "#!/opt/perl64/bin/perl".

Acknowledgements

Perl 5.24.1 represents approximately 8 months of development since Perl 5.24.0 and contains approximately
8,100 lines of changes across 240 files from 18 authors.

Excluding auto-generated files, documentation and release tools, there were approximately 2,200 lines of
changes to 170 .pm, .t, .c and .h files.

Perl continues to flourish into its third decade thanks to a vibrant community of users and developers.
The following people are known to have contributed the improvements that became Perl 5.24.1:

Aaron Crane, Alex Vandiver, Aristotle Pagaltzis, Chad Granum, Chris 'BinGOs' Williams, Craig A. Berry,
Father Chrysostomos, James E Keenan, Jarkko Hietaniemi, Karen Etheridge, Leon Timmermans, Matthew
Horsfall, Ricardo Signes, Sawyer X, Sébastien Aperghis-Tramoni, Stevan Little, Steve Hay, Tony Cook.

The list above is almost certainly incomplete as it is automatically generated from version control
history. In particular, it does not include the names of the (very much appreciated) contributors who
reported issues to the Perl bug tracker.

Many of the changes included in this version originated in the CPAN modules included in Perl's core.
We're grateful to the entire CPAN community for helping Perl to flourish.

For a more complete list of all of Perl's historical contributors, please see the AUTHORS file in the
Perl source distribution.

Reporting Bugs

       If  you  find  what  you  think  is  a  bug,  you  might  check  the  articles  recently  posted  to  the
       comp.lang.perl.misc  newsgroup  and  the Perl bug database at <https://rt.perl.org/> .  There may also be
       information at <http://www.perl.org/> , the Perl Home Page.

       If you believe you have an unreported bug, please run the perlbug program included with your release.  Be
       sure to trim your bug down to a tiny but sufficient test case.  Your bug report, along with the output of
       "perl -V", will be sent off to perlbug@perl.org to be analysed by the Perl porting team.

       If the bug you are reporting has security implications which make it inappropriate to send to a  publicly
       archived  mailing  list,  then see "SECURITY VULNERABILITY CONTACT INFORMATION" in perlsec for details of
       how to report the issue.