linux-hardening - Re: [PATCH 0/5] pstore: Use zstd directly by default for compression

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Date:   Tue, 18 Oct 2022 16:38:39 +0200
From:   Ard Biesheuvel <ardb@...nel.org>
To:     "Guilherme G. Piccoli" <gpiccoli@...lia.com>
Cc:     Kees Cook <keescook@...omium.org>, Tony Luck <tony.luck@...el.com>,
        Nick Terrell <terrelln@...com>, linux-kernel@...r.kernel.org,
        linux-hardening@...r.kernel.org
Subject: Re: [PATCH 0/5] pstore: Use zstd directly by default for compression

On Tue, 18 Oct 2022 at 16:11, Guilherme G. Piccoli <gpiccoli@...lia.com> wrote:
>
> On 18/10/2022 05:20, Ard Biesheuvel wrote:
> > [...]
> > So again, I suggest to simply drop this non-feature, and standardize
> > on either zlib or zstd using the library interface exclusively. If
> > someone present a compelling use case, we can always consider adding
> > it back in some form.
> >
> > As for the choice of algorithm, given the equal performance using the
> > default compression level, and the difference in code size, I don't
> > see why zstd should be preferred here. If anything, it only increases
> > the likelihood of hitting another error if we are panicking due to
> > some memory corruption issue.
>
> I think it's a good argument - would zlib be simpler in code than zstd?

I think it should be rather straight-forward. Note that this is what
we had before 2016 when all the 'features' were starting to get added.

> I've checked the zstd patch from Kees - not complex per se, but would be
> great if we could have a simple mechanism, without the need of the ifdef
> there for example...
>
> Cheers,
>
>
> Guilherme