From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932953AbeD0Pi7 (ORCPT ); Fri, 27 Apr 2018 11:38:59 -0400 Received: from frisell.zx2c4.com ([192.95.5.64]:42891 "EHLO frisell.zx2c4.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932455AbeD0Pi5 (ORCPT ); Fri, 27 Apr 2018 11:38:57 -0400 X-Google-Smtp-Source: AB8JxZqkeBXBpe1GsarEkeINS3odtNhjQAlONahZXazNsei3Fectg7HoiMwwgJfVn/FSHjKhYND/WZrKF6D4PxgJF/k= MIME-Version: 1.0 In-Reply-To: <20180427000013.GH5965@thunk.org> References: <20180426050056.GF18803@thunk.org> <20180426073255.GH18803@thunk.org> <20180426192524.GD5965@thunk.org> <2add15cb-2113-0504-a732-81255ea61bf5@gmail.com> <20180426204748.GA7540@gmail.com> <20180427000013.GH5965@thunk.org> From: "Jason A. Donenfeld" Date: Fri, 27 Apr 2018 17:38:52 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: Linux messages full of `random: get_random_u32 called from` To: "Theodore Y. Ts'o" , Christian Brauner , Sultan Alsawaf , LKML , Jann Horn Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Ted, Please correct me if I'm wrong, but my present understanding of this is that crng readiness used to be broken, meaning people would have a seeded rng without it actually being seeded. You fixed this bug, and now people are discovering that they don't have crng readiness during a late stage of their init, which is breaking all sorts of entirely reasonable and widely deployed userspaces. You could argue that those userspaces were "only designed for machines that have enough [by what measure?] boot time entropy", but obviously they didn't have that in mind. And now here we have an example of an ordinary x86 machine -- not some weird embedded device -- hitting these issues. I'd suspect that the problem here isn't one that we can exclusively punt onto userspace. Sultan mentioned that his machine actually does trigger large quantities of interrupts. Is it possible that the entropy gathering algorithm has some issues, and Sultan's report points to a real bug here? Considering the crng readiness state hasn't been working until your recent fix, I suspect the actual entropy gathering code probably hasn't prompted too many bug reports, until now that is. Jason