linux-hardening - [PATCH v3 0/2] pstore: Replace crypto API compression with zlib calls

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Date:   Wed, 12 Jul 2023 18:23:30 +0200
From:   Ard Biesheuvel <ardb@...nel.org>
To:     linux-hardening@...r.kernel.org
Cc:     Ard Biesheuvel <ardb@...nel.org>,
        Kees Cook <keescook@...omium.org>,
        "Guilherme G. Piccoli" <gpiccoli@...lia.com>,
        Eric Biggers <ebiggers@...nel.org>
Subject: [PATCH v3 0/2] pstore: Replace crypto API compression with zlib calls

The pstore layer implements support for compression of kernel log
output, using a variety of compression algorithms provided by the
[deprecated] crypto API 'comp' interface.

This appears to have been somebody's pet project rather than a solution
to a real problem: the original deflate compression is reasonably fast,
compresses well and is comparatively small in terms of code footprint,
and so the flexibility that the crypto API integration provides does
little more than complicate the code for no reason.

So let's get rid of this complexity, and switch back to zlib deflate
using the library interface.

Changes since v2:
- some more prose improvements and NULL checks/assignments suggested by
  Eric
- reset author on patch #1
- add Guilherme's Tested-by

Changes since v1:
- add missing vfree() of zlib compression workspace
- implement improvements and simplifications suggested by Eric
- add missing zlib_in/deflateEnd() calls
- add code comment to document that the use of a library interface is
  deliberate, and doesn't require a future 'upgrade' to the crypto API

Cc: Kees Cook <keescook@...omium.org>
Cc: "Guilherme G. Piccoli" <gpiccoli@...lia.com>
Cc: Eric Biggers <ebiggers@...nel.org>

Ard Biesheuvel (2):
  pstore: Remove worst-case compression size logic
  pstore: Replace crypto API compression with zlib_deflate library calls

 fs/pstore/Kconfig    | 100 +-----
 fs/pstore/platform.c | 330 ++++++--------------
 2 files changed, 110 insertions(+), 320 deletions(-)

-- 
2.39.2