oss-security - Perl 5.32.0 mishandling of rpath and runpath tokens

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Date: Mon, 20 Jul 2020 04:21:51 -0400
From: Jeffrey Walton <noloader@...il.com>
To: oss-security@...ts.openwall.com
Subject: Perl 5.32.0 mishandling of rpath and runpath tokens

Hi Everyone,

Perl mishandles rpath tokens $ORIGIN, $LIB and $PLATFORM. Also see
https://man7.org/linux/man-pages/man8/ld.so.8.html.

Building on Linux or Solaris with LDFLAGS that includes a rpath or runpath:

    -Wl,-R,$ORIGIN/../lib -Wl,-R,$HOME/tmp/ok2delete/lib

results in a rpath or runpath similar to below (Solaris is shown):

    # From $HOME/perl-5.32.0 directory
    $ elfdump libperl.so | grep PATH
    [10]  RUNPATH         0xaf4d
/../lib:/export/home/jwalton/tmp/ok2delete/lib
    [11]  RPATH           0xaf4d
/../lib:/export/home/jwalton/tmp/ok2delete/lib

Now the interesting thing here is, $ORIGIN was expanded to nothing and
/../lib is just /lib. And Solaris /lib directory contains old
libraries, like zLib 1.2.8 and Bzip 1.0.6. zLib 1.2.8 and Bzip 1.0.6
have CVEs against them. So rather than use the new zLib and Bzip in
$HOME/tmp/ok2delete/lib, Perl uses the old ones with CVEs in /lib.

Perl stated they won't fix the problem. Also see
https://github.com/Perl/perl5/issues/17534.

The best workarounds I have found is to run patchelf (Linux) or
editelf (Solaris) on all programs and libraries after 'make' and
before 'make check', and after 'make check' and before 'make install'.
The procedure has to happen twice because Perl rebuilds some things
after 'make', including some shared objects built during 'make check'.

The problem with the workaround is, patchelf and editelf has limited
availability. patchelf is buggy [1,2] and editelf is only available on
Solaris 11 [3].

[1] https://bugzilla.redhat.com/show_bug.cgi?id=1497012
[2] https://bugs.launchpad.net/ubuntu/+source/patchelf/+bug/1888175
[3] https://blogs.oracle.com/solaris/avoiding-ldlibrarypath%3a-the-options-v2

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