linux-kernel - Re: [PATCH v3 2/5] efi: stub: use random seed from EFI variable

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Message-ID: <20221128013523.GA6780@srcf.ucam.org>
Date:   Mon, 28 Nov 2022 01:35:23 +0000
From:   Matthew Garrett <mjg59@...f.ucam.org>
To:     "Jason A. Donenfeld" <Jason@...c4.com>
Cc:     linux-efi@...r.kernel.org, linux-crypto@...r.kernel.org,
        patches@...ts.linux.dev, linux-kernel@...r.kernel.org,
        ardb@...nel.org
Subject: Re: [PATCH v3 2/5] efi: stub: use random seed from EFI variable

On Mon, Nov 28, 2022 at 02:12:38AM +0100, Jason A. Donenfeld wrote:

> Yea this is a bummer. During my first attempt at this, I actually
> overwrote the whole thing with zeros and then deleted it. But Ard
> pointed out that this doesn't make a difference anyway. But, as it turns
> out, that's more or less the same thing that happens with seed files on
> SSDs (nobody calls fstrim after overwriting a seed file). So at the very
> least, it's no worse?

Anyone with the ability to directly read the flash variable store is 
almost certainly in a position to do worse things, so I wouldn't worry 
about it.