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Date:   Mon, 16 Sep 2019 18:23:56 -0700
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To:     Linus Torvalds <torvalds@linux-foundation.org>,
        "Ahmed S. Darwish" <darwish.07@gmail.com>
CC:     "Theodore Y. Ts'o" <tytso@mit.edu>, Willy Tarreau <w@1wt.eu>,
        Vito Caputo <vcaputo@pengaru.com>,
        Lennart Poettering <mzxreary@0pointer.de>,
        Andreas Dilger <adilger.kernel@dilger.ca>,
        Jan Kara <jack@suse.cz>, Ray Strode <rstrode@redhat.com>,
        William Jon McCann <mccann@jhu.edu>,
        "Alexander E. Patrakov" <patrakov@gmail.com>,
        zhangjs <zachary@baishancloud.com>, linux-ext4@vger.kernel.org,
        lkml <linux-kernel@vger.kernel.org>
From:   Matthew Garrett <mjg59@srcf.ucam.org>
Message-ID: <BEF07E89-E36D-480F-AB1E-25C80C9DABE7@srcf.ucam.org>
Subject: Re: Linux 5.3-rc8
Sender: linux-ext4-owner@vger.kernel.org
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On 16 September 2019 18:05:57 GMT-07:00, Linus Torvalds <torvalds@linux-fou=
ndation=2Eorg> wrote:
>On Mon, Sep 16, 2019 at 4:29 PM Ahmed S=2E Darwish <darwish=2E07@gmail=2E=
com>
>wrote:
>>
>> Linus, in all honesty, the other case is _not_ a hypothetical =2E
>
>Oh yes it is=2E
>
>You're confusing "use" with "breakage"=2E
>
>The _use_ of getrandom(0) for key generation isn't hypothetical=2E
>
>But the _breakage_ from the suggested patch that makes it time out is=2E
>
>See the difference?
>
>The thing is, to break, you have to
>
> (a) do that key generation at boot time
>
> (b) do it on an idle machine that doesn't have entropy

Exactly the scenario where you want getrandom() to block, yes=2E=20

>in order to basically reproduce the current boot-time hang situation
>with the broken gdm, except with an actual "generate key"=2E
>
>Then you have to ignore the big warning too=2E

The big warning that's only printed in dmesg?=20


--=20
Matthew Garrett | mjg59@srcf=2Eucam=2Eorg