linux-hardening - Re: [PATCH v2 1/2] pstore: Remove worst-case compression size logic

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Message-ID: <20230708021807.GB1731@sol.localdomain>
Date:   Fri, 7 Jul 2023 19:18:07 -0700
From:   Eric Biggers <ebiggers@...nel.org>
To:     Ard Biesheuvel <ardb@...nel.org>
Cc:     linux-hardening@...r.kernel.org, Kees Cook <keescook@...omium.org>,
        "Guilherme G. Piccoli" <gpiccoli@...lia.com>
Subject: Re: [PATCH v2 1/2] pstore: Remove worst-case compression size logic

On Fri, Jul 07, 2023 at 10:34:55AM +0200, Ard Biesheuvel wrote:
> From: Kees Cook <keescook@...omium.org>

As was mentioned by others, you should reset the author.

> +	/* Worst-case compression should never be more than uncompressed. */
> +	buf = kmalloc(psinfo->bufsize, GFP_KERNEL);

I don't think the above comment really conveys the reasoning.  Maybe write
something along the lines of:

	/*
         * The compression buffer only needs to be as large as the maximum
         * uncompressed record size, since any record that would be expanded by
         * compression is just stored uncompressed.
	 */

- Eric