linux-kernel - Re: [PATCH 5/8] pstore: Fix long-term implicit conversions in the compression routines

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Message-ID: <202210071234.D289C8C@keescook>
Date:   Fri, 7 Oct 2022 12:37:32 -0700
From:   Kees Cook <keescook@...omium.org>
To:     Ard Biesheuvel <ardb@...nel.org>
Cc:     "Guilherme G. Piccoli" <gpiccoli@...lia.com>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        kernel-dev@...lia.com, kernel@...ccoli.net, anton@...msg.org,
        ccross@...roid.com, tony.luck@...el.com
Subject: Re: [PATCH 5/8] pstore: Fix long-term implicit conversions in the
 compression routines

On Fri, Oct 07, 2022 at 10:47:01AM +0200, Ard Biesheuvel wrote:
> On Fri, 7 Oct 2022 at 01:36, Kees Cook <keescook@...omium.org> wrote:
> >
> > On Thu, Oct 06, 2022 at 07:42:09PM -0300, Guilherme G. Piccoli wrote:
> > > The pstore infrastructure is capable of compressing collected logs,
> > > relying for that in many compression "libraries" present on kernel.
> > > Happens that the (de)compression code in pstore performs many
> > > implicit conversions from unsigned int/size_t to int, and vice-versa.
> > > Specially in the compress buffer size calculation, we notice that
> > > even the libs are not consistent, some of them return int, most of
> > > them unsigned int and others rely on preprocessor calculation.
> > >
> > > Here is an attempt to make it consistent: since we're talking
> > > about buffer sizes, let's go with unsigned types, since negative
> > > sizes don't make sense.
> >
> > Thanks for this! I want to go through this more carefully, but I'm a fan
> > of the clean-up. I'd also like to get Ard's compression refactor landed
> > again, and then do this on top of it.
> >
> 
> Isn't this the stuff we want to move into the crypto API?

It is, yes. Guilherme, for background:
https://lore.kernel.org/linux-crypto/20180802215118.17752-1-keescook@chromium.org/

-- 
Kees Cook