linux-kernel - Re: [PATCH 1/1 v9] use crc32 instead of md5 for hibernation e820 integrity check

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Message-ID: <YH4BUx4Jkx8NtXtw@gmail.com>
Date:   Mon, 19 Apr 2021 15:16:51 -0700
From:   Eric Biggers <ebiggers@...nel.org>
To:     Chris von Recklinghausen <crecklin@...hat.com>
Cc:     ardb@...nel.org, simo@...hat.com, rafael@...nel.org,
        decui@...rosoft.com, linux-pm@...r.kernel.org,
        linux-crypto@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/1 v9] use crc32 instead of md5 for hibernation e820
 integrity check

On Fri, Apr 16, 2021 at 09:16:55AM -0400, Chris von Recklinghausen wrote:
> Hibernation fails on a system in fips mode because md5 is used for the e820
> integrity check and is not available. Use crc32 instead.

Doesn't the commit title need to be prefixed with something like "x86/power"?

> The check is intended to detect whether the E820 memory map provided
> by the firmware after cold boot unexpectedly differs from the one that
> was in use when the hibernation image was created. In this case, the
> hibernation image cannot be restored, as it may cover memory regions
> that are no longer available to the OS.
> 
> A non-cryptographic checksum such as CRC-32 is sufficient to detect such
> inadvertent deviations.
> 
> Fixes: 62a03defeabd ("PM / hibernate: Verify the consistent of e820 memory map
>        by md5 digest")

The "Fixes" line shouldn't be line-wrapped.

Otherwise this looks fine.  The explanation in the commit message still isn't
great, but it's much better than it was before.

You can add:

	Reviewed-by: Eric Biggers <ebiggers@...gle.com>

- Eric