linux-ext4 - Re: Linux 5.3-rc8

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Message-ID: <C4F7DC65-50B9-4D70-8E9B-0A6FF5C1070A@srcf.ucam.org>
Date:   Mon, 16 Sep 2019 18:46:07 -0700
From:   Matthew Garrett <mjg59@...f.ucam.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
CC:     "Ahmed S. Darwish" <darwish.07@...il.com>,
        "Theodore Y. Ts'o" <tytso@....edu>, Willy Tarreau <w@....eu>,
        Vito Caputo <vcaputo@...garu.com>,
        Lennart Poettering <mzxreary@...inter.de>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        Jan Kara <jack@...e.cz>, Ray Strode <rstrode@...hat.com>,
        William Jon McCann <mccann@....edu>,
        "Alexander E. Patrakov" <patrakov@...il.com>,
        zhangjs <zachary@...shancloud.com>, linux-ext4@...r.kernel.org,
        lkml <linux-kernel@...r.kernel.org>
Subject: Re: Linux 5.3-rc8

On 16 September 2019 18:41:36 GMT-07:00, Linus Torvalds <torvalds@...ux-foundation.org> wrote:
>On Mon, Sep 16, 2019 at 6:24 PM Matthew Garrett <mjg59@...f.ucam.org>
>wrote:
>>
>> Exactly the scenario where you want getrandom() to block, yes.
>
>It *would* block. Just not forever.

It's already not forever - there's enough running in the background of that system that it'll unblock eventually. 

>And btw, the whole "generate key at boot when nothing else is going
>on" is already broken, so presumably nobody actually does it.

If nothing ever did this, why was getrandom() designed in a way to protect against this situation? 

>See why I'm saying "hypothetical"? You're doing it again.
>
>> >Then you have to ignore the big warning too.
>>
>> The big warning that's only printed in dmesg?
>
>Well, the patch actually made getrandom() return en error too, but you
>seem more interested in the hypotheticals than in arguing actualities.

If you want to be safe, terminate the process.


-- 
Matthew Garrett | mjg59@...f.ucam.org