Re: [tech-board] [PATCH 00/11] xz: Updates to license, filters, and compression options

From: Jonathan Corbet <corbet@lwn.net>
To: Kees Cook <keescook@chromium.org>,
	Andrew Morton <akpm@linux-foundation.org>
Cc: Lasse Collin <lasse.collin@tukaani.org>,
	Jia Tan <jiat0218@gmail.com>,
	linux-kernel@vger.kernel.org
Subject: Re: [tech-board] [PATCH 00/11] xz: Updates to license, filters, and compression options
Date: Fri, 29 Mar 2024 14:51:41 -0600	[thread overview]
Message-ID: <87h6go3go2.fsf@meer.lwn.net> (raw)
In-Reply-To: <202403291221.124220E0F4@keescook>

"Kees Cook" <keescook@chromium.org> writes:

> On Wed, Mar 20, 2024 at 08:38:33PM +0200, Lasse Collin wrote:
>> XZ Embedded, the upstream project, switched from public domain to the
>> BSD Zero Clause License (0BSD). Now matching SPDX license identifiers
>> can be added.
>> 
>> The new ARM64 and RISC-V filters can be used by Squashfs.
>> 
>> Account for the default threading change made in the xz command line
>> tool version 5.6.0. Tweak kernel compression options for archs that
>> support XZ compressed kernel.
>> 
>> Documentation was revised. There are minor cleanups too.
>> 
>> Lasse Collin (11):
>>   MAINTAINERS: Add XZ Embedded maintainers
>>   LICENSES: Add 0BSD license text
>>   xz: Switch from public domain to BSD Zero Clause License (0BSD)
>>   xz: Documentation/staging/xz.rst: Revise thoroughly
>>   xz: Fix comments and coding style
>>   xz: Cleanup CRC32 edits from 2018
>>   xz: Optimize for-loop conditions in the BCJ decoders
>>   xz: Add ARM64 BCJ filter
>>   xz: Add RISC-V BCJ filter
>>   xz: Use 128 MiB dictionary and force single-threaded mode
>>   xz: Adjust arch-specific options for better kernel compression
>> 
>>  Documentation/staging/xz.rst    | 130 ++++++++---------------
>>  LICENSES/deprecated/0BSD        |  23 ++++
>>  MAINTAINERS                     |  14 +++
>>  include/linux/decompress/unxz.h |   5 +-
>>  include/linux/xz.h              |   5 +-
>>  init/Kconfig                    |   5 +-
>>  lib/decompress_unxz.c           |  39 ++++---
>>  lib/xz/Kconfig                  |  13 ++-
>>  lib/xz/xz_crc32.c               |   7 +-
>>  lib/xz/xz_dec_bcj.c             | 183 ++++++++++++++++++++++++++++++--
>>  lib/xz/xz_dec_lzma2.c           |   5 +-
>>  lib/xz/xz_dec_stream.c          |   5 +-
>>  lib/xz/xz_dec_syms.c            |  16 +--
>>  lib/xz/xz_dec_test.c            |  12 +--
>>  lib/xz/xz_lzma2.h               |   5 +-
>>  lib/xz/xz_private.h             |  20 ++--
>>  lib/xz/xz_stream.h              |   7 +-
>>  scripts/Makefile.lib            |  13 ++-
>>  scripts/xz_wrap.sh              | 157 +++++++++++++++++++++++++--
>>  19 files changed, 487 insertions(+), 177 deletions(-)
>>  create mode 100644 LICENSES/deprecated/0BSD
>
> Andrew (and anyone else), please do not take this code right now.
>
> Until the backdooring of upstream xz[1] is fully understood, we should not
> accept any code from Jia Tan, Lasse Collin, or any other folks associated
> with tukaani.org. It appears the domain, or at least credentials
> associated with Jia Tan, have been used to create an obfuscated ssh
> server backdoor via the xz upstream releases since at least 5.6.0.
> Without extensive analysis, we should not take any associated code.
> It may be worth doing some retrospective analysis of past contributions
> as well...
>
> Lasse, are you able to comment about what is going on here?

FWIW, it looks like this series has been in linux-next for a few days.
Maybe it needs to come out, for now at least?

jon