Cwd::fast_abs_path's untaint should allow for multiline directories #12624

p5pRT · 2012-12-01T16:47:35Z

Migrated from rt.perl.org#115962 (status was 'resolved')

Searchable as RT115962$

p5pRT · 2012-12-01T16:47:36Z

From [email protected]

This is a bug report for perl from joel.a.berger@gmail.com,
generated with the help of perlbug 1.39 running under perl 5.16.0.

From f735a80fac061ee49ac9a1d6552de229d6e2cc10 Mon Sep 17 00:00:00 2001
From: Joel Berger <joel.a.berger@gmail.com>
Date: Sat, 1 Dec 2012 10:15:36 -0600
Subject: [PATCH] Cwd::fast_abs_path's untaint should allow for multiline
directories
MIME-Version: 1.0
Content-Type: multipart/mixed; boundary="------------1.7.9.5"

This is a multi-part message in MIME format.
--------------1.7.9.5
Content-Type: text/plain; charset=UTF-8; format=fixed
Content-Transfer-Encoding: 8bit

This bug was noticed via Perl-Toolchain-Gang/File-chdir#3 and testing has led to this being the cause.
The problem is worse on some platforms (notably cygwin in this case) when abs_path is implemented by fast_abs_path.
Since File::chdir tests for proper behavior when a directory contains a newline, this bug then breaks File::chdir (one of my favorites and very useful xplatform tool).

Yes this should have tests, but since it will involve creating a directory with a newline, I thought I would do better to leave that to someone with better knowledge than I.

dist/Cwd/Cwd.pm | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

--------------1.7.9.5
Content-Type: text/x-patch; name="0001-Cwd-fast_abs_path-s-untaint-should-allow-for-multili.patch"
Content-Transfer-Encoding: 8bit
Content-Disposition: attachment; filename="0001-Cwd-fast_abs_path-s-untaint-should-allow-for-multili.patch"

Inline Patch

diff --git a/dist/Cwd/Cwd.pm b/dist/Cwd/Cwd.pm
index f772bf4..888c505 100644
--- a/dist/Cwd/Cwd.pm
+++ b/dist/Cwd/Cwd.pm
@@ -624,8 +624,8 @@ sub fast_abs_path {
 
     # Detaint else we'll explode in taint mode.  This is safe because
     # we're not doing anything dangerous with it.
-    ($path) = $path =~ /(.*)/;
-    ($cwd)  = $cwd  =~ /(.*)/;
+    ($path) = $path =~ /(.*)/s;
+    ($cwd)  = $cwd  =~ /(.*)/s;
 
     unless (-e $path) {
  	_croak("$path: No such file or directory");

--------------1.7.9.5--


---

Flags: category=core severity=medium

Site configuration information for perl 5.16.0:

Configured by joel at Tue May 22 11:06:05 CDT 2012.

Summary of my perl5 (revision 5 version 16 subversion 0) configuration:

Platform:
osname=linux, osvers=3.2.0-23-generic, archname=x86_64-linux
uname='linux joel-ubuntu 3.2.0-23-generic #36-ubuntu smp tue apr 10 20:39:51 utc 2012 x86_64 x86_64 x86_64 gnulinux '
config_args='-de -Dprefix=/home/joel/perl5/perlbrew/perls/perl-5.16.0'
hint=recommended, useposix=true, d_sigaction=define
useithreads=undef, usemultiplicity=undef
useperlio=define, d_sfio=undef, uselargefiles=define, usesocks=undef
use64bitint=define, use64bitall=define, uselongdouble=undef
usemymalloc=n, bincompat5005=undef
Compiler:
cc='cc', ccflags ='-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64',
optimize='-O2',
cppflags='-fno-strict-aliasing -pipe -fstack-protector -I/usr/local/include'
ccversion='', gccversion='4.6.3', gccosandvers=''
intsize=4, longsize=8, ptrsize=8, doublesize=8, byteorder=12345678
d_longlong=define, longlongsize=8, d_longdbl=define, longdblsize=16
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 -L/usr/local/lib'
libpth=/usr/local/lib /lib/x86_64-linux-gnu /lib/../lib /usr/lib/x86_64-linux-gnu /usr/lib/../lib /lib /usr/lib
libs=-lnsl -ldl -lm -lcrypt -lutil -lc
perllibs=-lnsl -ldl -lm -lcrypt -lutil -lc
libc=, so=so, useshrplib=false, libperl=libperl.a
gnulibc_version='2.15'
Dynamic Linking:
dlsrc=dl_dlopen.xs, dlext=so, d_dlsymun=undef, ccdlflags='-Wl,-E'
cccdlflags='-fPIC', lddlflags='-shared -O2 -L/usr/local/lib -fstack-protector'

Locally applied patches:

@INC for perl 5.16.0:
/home/joel/perl5/perlbrew/perls/perl-5.16.0/lib/site_perl/5.16.0/x86_64-linux
/home/joel/perl5/perlbrew/perls/perl-5.16.0/lib/site_perl/5.16.0
/home/joel/perl5/perlbrew/perls/perl-5.16.0/lib/5.16.0/x86_64-linux
/home/joel/perl5/perlbrew/perls/perl-5.16.0/lib/5.16.0
.

Environment for perl 5.16.0:
HOME=/home/joel
LANG=en_US.UTF-8
LANGUAGE (unset)
LD_LIBRARY_PATH (unset)
LOGDIR (unset)
PATH=/usr/local/heroku/bin:/home/joel/perl5/perlbrew/bin:/home/joel/perl5/perlbrew/perls/perl-5.16.0/bin:/home/joel/.rvm/gems/ruby-1.9.2-p320/bin:/home/joel/.rvm/gems/ruby-1.9.2-p320@global/bin:/home/joel/.rvm/rubies/ruby-1.9.2-p320/bin:/home/joel/.rvm/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/home/joel/bin:/home/joel/.rvm/bin
PERLBREW_BASHRC_VERSION=0.42
PERLBREW_HOME=/home/joel/.perlbrew
PERLBREW_MANPATH=/home/joel/perl5/perlbrew/perls/perl-5.16.0/man
PERLBREW_PATH=/home/joel/perl5/perlbrew/bin:/home/joel/perl5/perlbrew/perls/perl-5.16.0/bin
PERLBREW_PERL=perl-5.16.0
PERLBREW_ROOT=/home/joel/perl5/perlbrew
PERLBREW_VERSION=0.42
PERL_BADLANG (unset)
SHELL=/bin/bash

p5pRT · 2012-12-02T16:58:32Z

From @jkeenan

On Sat Dec 01 08:47:36 2012, joel.a.berger@gmail.com wrote:

This is a bug report for perl from joel.a.berger@gmail.com,
generated with the help of perlbug 1.39 running under perl 5.16.0.

[snip]

This bug was noticed via https://github.com/dagolden/file-
chdir/issues/3 and testing has led to this being the cause.
The problem is worse on some platforms (notably cygwin in this case)
when abs_path is implemented by fast_abs_path.
Since File::chdir tests for proper behavior when a directory contains
a newline, this bug then breaks File::chdir (one of my favorites
and very useful xplatform tool).

Yes this should have tests, but since it will involve creating a
directory with a newline, I thought I would do better to leave that
to someone with better knowledge than I.

Apart from the mechanics of creating a directory with a newline in its
name, what should the test be testing?

p5pRT · 2012-12-02T16:58:32Z

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

p5pRT · 2012-12-02T17:11:43Z

From [email protected]

As seen in the bug report on File::chdir (
Perl-Toolchain-Gang/File-chdir#3 (comment)),
simply calling Cwd::fast_abs_path when in such a directory dies. As I say
there, it is even worse since this function is aliased as Cwd::abs_path on
some platforms. Therefore the tests should be that fast_abs_path doesn't
die when inside a directory with a newline in it.

Further, I haven't search the rest of the codebase but I suspect that all
untaint patterns like /(.*)/ are broken without the /s.

Joel

On Sun, Dec 2, 2012 at 10:58 AM, James E Keenan via RT <
perlbug-followup@perl.org> wrote:

On Sat Dec 01 08:47:36 2012, joel.a.berger@gmail.com wrote:

This is a bug report for perl from joel.a.berger@gmail.com,
generated with the help of perlbug 1.39 running under perl 5.16.0.

[snip]

This bug was noticed via https://github.com/dagolden/file-
chdir/issues/3 and testing has led to this being the cause.
The problem is worse on some platforms (notably cygwin in this case)
when abs_path is implemented by fast_abs_path.
Since File::chdir tests for proper behavior when a directory contains
a newline, this bug then breaks File::chdir (one of my favorites
and very useful xplatform tool).

Yes this should have tests, but since it will involve creating a
directory with a newline, I thought I would do better to leave that
to someone with better knowledge than I.

Apart from the mechanics of creating a directory with a newline in its
name, what should the test be testing?

p5pRT · 2012-12-03T11:37:52Z

From @epa

Could I suggest that an untaint() builtin would be a good idea?

p5pRT · 2012-12-03T16:55:03Z

From @cpansprout

On Sun Dec 02 09:11:43 2012, joel.a.berger@gmail.com wrote:

As seen in the bug report on File::chdir (
Perl-Toolchain-Gang/File-chdir#3 (comment)),
simply calling Cwd::fast_abs_path when in such a directory dies. As I say
there, it is even worse since this function is aliased as Cwd::abs_path on
some platforms. Therefore the tests should be that fast_abs_path doesn't
die when inside a directory with a newline in it.

Further, I haven't search the rest of the codebase but I suspect that all
untaint patterns like /(.*)/ are broken without the /s.

Such as File::Path:

for ($arg->{cwd}) { /\A(.*)\Z/; $_ = $1 } # untaint

I tried writing a test for your bug using File::Temp, and ran into this
problem, which I have reported at
<https://rt.cpan.org/Ticket/Display.html?id=81665>.

In the end I wrote a test without using File::Temp (commit 52ee8d0)
and applied your patch as 9f28c63. Thank you.

--

Father Chrysostomos

p5pRT · 2012-12-03T16:55:03Z

From [Unknown Contact. See original ticket]

On Sun Dec 02 09:11:43 2012, joel.a.berger@gmail.com wrote:

As seen in the bug report on File::chdir (
Perl-Toolchain-Gang/File-chdir#3 (comment)),
simply calling Cwd::fast_abs_path when in such a directory dies. As I say
there, it is even worse since this function is aliased as Cwd::abs_path on
some platforms. Therefore the tests should be that fast_abs_path doesn't
die when inside a directory with a newline in it.

Further, I haven't search the rest of the codebase but I suspect that all
untaint patterns like /(.*)/ are broken without the /s.

Such as File::Path:

for ($arg->{cwd}) { /\A(.*)\Z/; $_ = $1 } # untaint

I tried writing a test for your bug using File::Temp, and ran into this
problem, which I have reported at
<https://rt.cpan.org/Ticket/Display.html?id=81665>.

In the end I wrote a test without using File::Temp (commit 52ee8d0)
and applied your patch as 9f28c63. Thank you.

--

Father Chrysostomos

p5pRT · 2012-12-03T16:55:03Z

@cpansprout - Status changed from 'open' to 'resolved'

p5pRT closed this as completed Dec 3, 2012

p5pRT added Severity Medium distro-All hasPatch type-library labels Oct 19, 2019

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Cwd::fast_abs_path's untaint should allow for multiline directories #12624

Cwd::fast_abs_path's untaint should allow for multiline directories #12624

p5pRT commented Dec 1, 2012

p5pRT commented Dec 1, 2012

p5pRT commented Dec 2, 2012

p5pRT commented Dec 2, 2012

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p5pRT commented Dec 3, 2012

Cwd::fast_abs_path's untaint should allow for multiline directories #12624

Cwd::fast_abs_path's untaint should allow for multiline directories #12624

Comments

p5pRT commented Dec 1, 2012

p5pRT commented Dec 1, 2012

From [email protected]

p5pRT commented Dec 2, 2012

From @jkeenan

p5pRT commented Dec 2, 2012

p5pRT commented Dec 2, 2012

From [email protected]

p5pRT commented Dec 3, 2012

From @epa

p5pRT commented Dec 3, 2012

From @cpansprout

p5pRT commented Dec 3, 2012

From [Unknown Contact. See original ticket]

p5pRT commented Dec 3, 2012