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

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Date:   Thu, 6 Oct 2022 16:36:55 -0700
From:   Kees Cook <keescook@...omium.org>
To:     "Guilherme G. Piccoli" <gpiccoli@...lia.com>
Cc:     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,
        Ard Biesheuvel <ardb@...nel.org>
Subject: Re: [PATCH 5/8] pstore: Fix long-term implicit conversions in the
 compression routines

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.

-- 
Kees Cook