From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.9 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SIGNED_OFF_BY,SPF_PASS autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E6C3DC00319 for ; Sun, 24 Feb 2019 18:25:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B848F206B6 for ; Sun, 24 Feb 2019 18:25:36 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="ES47LQyF" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727976AbfBXSZg (ORCPT ); Sun, 24 Feb 2019 13:25:36 -0500 Received: from mail-wm1-f65.google.com ([209.85.128.65]:36750 "EHLO mail-wm1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726206AbfBXSZf (ORCPT ); Sun, 24 Feb 2019 13:25:35 -0500 Received: by mail-wm1-f65.google.com with SMTP id j125so6068445wmj.1; Sun, 24 Feb 2019 10:25:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:openpgp:autocrypt:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=Is74wfUBl6pn9ZZRn/dFpKrxijO+z7ftlavk0sonjIQ=; b=ES47LQyF7Cdk7In15dXh8AWjTW1JVb2GNPknLfkCw9fZVxzJoWUHur+l1pan6hOQ7b PfdUGsLPB2s+VDvQQ285cxRphjOOLvIqK2ZCDSGW9LfZhXCH5yksi5sRvbdfPIhh4eGf g45LerNmjCTbA8L03+533itmFSM3of7VuoLtiEi1WJszpavJk/0FcKNzliML9TVYPTO+ xIbTYJSzDHBM4mVeu/udaz2F9UhEV7cJOnvogUrtERItrSb5nKb+1oyWPu9ftIAScoOW 7/uS1W8Jxf29RYtaXn1eqzZB7Ymt2PxytMf2/HWkFMZH0eP0GMgdllnLy5/yZXpM6YkR jSJA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:openpgp:autocrypt :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=Is74wfUBl6pn9ZZRn/dFpKrxijO+z7ftlavk0sonjIQ=; b=PpCa0DE2IxGgDiAgOEGWHje/P6N5lUKObuZQbZzf3AcJU0shA7ltunzqXrdMRqYqAx fhp4ordi7rYTM/M+fx3IJHqiu6zApYSfGWpQ5c+BsGyu3R2BQO4ZP7vJf0+WSBdMjtad 4VoiqK0zhOp/p580tHGYUrQwgah58V3OO4W3pun1iNmgWr40+hv7kBKN4ciExl/YIr84 JhsJgZoT5nWUKRCdq7IW/EDMxSjCZv00Xl+m1rAiurqPn9JMg6CscTuH/TUXmMGb+y/m pr+2vT12a8OzoP2oQqodmROKZZ7Yb78I84HtN5vdVAcaEhjDT1v2Nhc7pGzUU6Mns6wv TULA== X-Gm-Message-State: AHQUAubdPnmmi49IxnUQWpvC+olWWpeziQ/VJC4CWTVk1NbDcKYRPXk+ O1RFBDmdbRp3qav+vrO7Fv0= X-Google-Smtp-Source: AHgI3IaUkvacqFKH/8JBRKzjfKJ4qWWY3GOEaNZRG9+ER6BeEe+re+588hfHlwhwbhaQWfSpdwwz6A== X-Received: by 2002:a7b:c34c:: with SMTP id l12mr8096135wmj.147.1551032732546; Sun, 24 Feb 2019 10:25:32 -0800 (PST) Received: from ?IPv6:2a0b:e7c0:0:107::70f? ([2a0b:e7c0:0:107::70f]) by smtp.gmail.com with ESMTPSA id p16sm17642556wro.25.2019.02.24.10.25.31 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Sun, 24 Feb 2019 10:25:31 -0800 (PST) Subject: Re: [PATCH 4.20 11/50] signal: Always notice exiting tasks To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, stable@vger.kernel.org, Dmitry Vyukov , "Eric W. Biederman" References: <20190213183655.747168774@linuxfoundation.org> <20190213183656.733725215@linuxfoundation.org> <95a41702-ac6a-cd58-2ca5-71d879ee923c@gmail.com> <20190219090714.GA27102@kroah.com> From: Jiri Slaby Openpgp: preference=signencrypt Autocrypt: addr=jirislaby@gmail.com; prefer-encrypt=mutual; keydata= mQINBE6S54YBEACzzjLwDUbU5elY4GTg/NdotjA0jyyJtYI86wdKraekbNE0bC4zV+ryvH4j rrcDwGs6tFVrAHvdHeIdI07s1iIx5R/ndcHwt4fvI8CL5PzPmn5J+h0WERR5rFprRh6axhOk rSD5CwQl19fm4AJCS6A9GJtOoiLpWn2/IbogPc71jQVrupZYYx51rAaHZ0D2KYK/uhfc6neJ i0WqPlbtIlIrpvWxckucNu6ZwXjFY0f3qIRg3Vqh5QxPkojGsq9tXVFVLEkSVz6FoqCHrUTx wr+aw6qqQVgvT/McQtsI0S66uIkQjzPUrgAEtWUv76rM4ekqL9stHyvTGw0Fjsualwb0Gwdx ReTZzMgheAyoy/umIOKrSEpWouVoBt5FFSZUyjuDdlPPYyPav+hpI6ggmCTld3u2hyiHji2H cDpcLM2LMhlHBipu80s9anNeZhCANDhbC5E+NZmuwgzHBcan8WC7xsPXPaiZSIm7TKaVoOcL 9tE5aN3jQmIlrT7ZUX52Ff/hSdx/JKDP3YMNtt4B0cH6ejIjtqTd+Ge8sSttsnNM0CQUkXps w98jwz+Lxw/bKMr3NSnnFpUZaxwji3BC9vYyxKMAwNelBCHEgS/OAa3EJoTfuYOK6wT6nadm YqYjwYbZE5V/SwzMbpWu7Jwlvuwyfo5mh7w5iMfnZE+vHFwp/wARAQABtCBKaXJpIFNsYWJ5 IDxqaXJpc2xhYnlAZ21haWwuY29tPokCOwQTAQIAJQIbAwYLCQgHAwIGFQgCCQoLBBYCAwEC HgECF4AFAk6S6P4CGQEACgkQvSWxBAa0cEl1Sg//UMXp//d4lP57onXMC2y8gafT1ap/xuss IvXR+3jSdJCHRaUFTPY2hN0ahCAyBQq8puUa6zaXco5jIzsVjLGVfO/s9qmvBTKw9aP6eTU7 77RLssLlQYhRzh7vapRRp4xDBLvBGBv9uvWORx6dtRjh+e0J0nKKce8VEY+jiXv1NipWf+RV vg1gVbAjBnT+5RbJYtIDhogyuBFg14ECKgvy1Do6tg9Hr/kU4ta6ZBEUTh18Io7f0vr1Mlh4 yl2ytuUNymUlkA/ExBNtOhOJq/B087SmGwSLmCRoo5VcRIYK29dLeX6BzDnmBG+mRE63IrKD kf/ZCIwZ7cSbZaGo+gqoEpIqu5spIe3n3JLZQGnF45MR+TfdAUxNQ4F1TrjWyg5Fo30blYYU z6+5tQbaDoBbcSEV9bDt6UOhCx033TrdToMLpee6bUAKehsUctBlfYXZP2huZ5gJxjINRnlI gKTATBAXF+7vMhgyZ9h7eARG6LOdVRwhIFUMGbRCCMXrLLnQf6oAHyVnsZU1+JWANGFBjsyy fRP2+d8TrlhzN9FoIGYiKjATR9CpJZoELFuKLfKOBsc7DfEBpsdusLT0vlzR6JaGae78Od5+ ljzt88OGNyjCRIb6Vso0IqEavtGOcYG8R5gPhMV9n9/bCIVqM5KWJf/4mRaySZp7kcHyJSb0 O6m5Ag0ETpLnhgEQAM+cDWLL+Wvc9cLhA2OXZ/gMmu7NbYKjfth1UyOuBd5emIO+d4RfFM02 XFTIt4MxwhAryhsKQQcA4iQNldkbyeviYrPKWjLTjRXT5cD2lpWzr+Jx7mX7InV5JOz1Qq+P +nJWYIBjUKhI03ux89p58CYil24Zpyn2F5cX7U+inY8lJIBwLPBnc9Z0An/DVnUOD+0wIcYV nZAKDiIXODkGqTg3fhZwbbi+KAhtHPFM2fGw2VTUf62IHzV+eBSnamzPOBc1XsJYKRo3FHNe LuS8f4wUe7bWb9O66PPFK/RkeqNX6akkFBf9VfrZ1rTEKAyJ2uqf1EI1olYnENk4+00IBa+B avGQ8UW9dGW3nbPrfuOV5UUvbnsSQwj67pSdrBQqilr5N/5H9z7VCDQ0dhuJNtvDSlTf2iUF Bqgk3smln31PUYiVPrMP0V4ja0i9qtO/TB01rTfTyXTRtqz53qO5dGsYiliJO5aUmh8swVpo tgK4/57h3zGsaXO9PGgnnAdqeKVITaFTLY1ISg+Ptb4KoliiOjrBMmQUSJVtkUXMrCMCeuPD GHo739Xc75lcHlGuM3yEB//htKjyprbLeLf1y4xPyTeeF5zg/0ztRZNKZicgEmxyUNBHHnBK HQxz1j+mzH0HjZZtXjGu2KLJ18G07q0fpz2ZPk2D53Ww39VNI/J9ABEBAAGJAh8EGAECAAkF Ak6S54YCGwwACgkQvSWxBAa0cEk3tRAAgO+DFpbyIa4RlnfpcW17AfnpZi9VR5+zr496n2jH /1ldwRO/S+QNSA8qdABqMb9WI4BNaoANgcg0AS429Mq0taaWKkAjkkGAT7mD1Q5PiLr06Y/+ Kzdr90eUVneqM2TUQQbK+Kh7JwmGVrRGNqQrDk+gRNvKnGwFNeTkTKtJ0P8jYd7P1gZb9Fwj 9YLxjhn/sVIhNmEBLBoI7PL+9fbILqJPHgAwW35rpnq4f/EYTykbk1sa13Tav6btJ+4QOgbc ezWIwZ5w/JVfEJW9JXp3BFAVzRQ5nVrrLDAJZ8Y5ioWcm99JtSIIxXxt9FJaGc1Bgsi5K/+d yTKLwLMJgiBzbVx8G+fCJJ9YtlNOPWhbKPlrQ8+AY52Aagi9WNhe6XfJdh5g6ptiOILm330m kR4gW6nEgZVyIyTq3ekOuruftWL99qpP5zi+eNrMmLRQx9iecDNgFr342R9bTDlb1TLuRb+/ tJ98f/bIWIr0cqQmqQ33FgRhrG1+Xml6UXyJ2jExmlO8JljuOGeXYh6ZkIEyzqzffzBLXZCu jlYQDFXpyMNVJ2ZwPmX2mWEoYuaBU0JN7wM+/zWgOf2zRwhEuD3A2cO2PxoiIfyUEfB9SSmf faK/S4xXoB6wvGENZ85Hg37C7WDNdaAt6Xh2uQIly5grkgvWppkNy4ZHxE+jeNsU7tg= Message-ID: <07f0b789-b88b-8afd-6a36-354b3c2fb0ba@gmail.com> Date: Sun, 24 Feb 2019 19:25:30 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.5.0 MIME-Version: 1.0 In-Reply-To: <20190219090714.GA27102@kroah.com> Content-Type: text/plain; charset=iso-8859-2 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 19. 02. 19, 10:07, Greg Kroah-Hartman wrote: > On Tue, Feb 19, 2019 at 07:23:41AM +0100, Jiri Slaby wrote: >> On 13. 02. 19, 19:38, Greg Kroah-Hartman wrote: >>> 4.20-stable review patch. If anyone has any objections, please let me know. >>> >>> ------------------ >>> >>> From: Eric W. Biederman >>> >>> commit 35634ffa1751b6efd8cf75010b509dcb0263e29b upstream. >>> >>> Recently syzkaller was able to create unkillablle processes by >>> creating a timer that is delivered as a thread local signal on SIGHUP, >>> and receiving SIGHUP SA_NODEFERER. Ultimately causing a loop >>> failing to deliver SIGHUP but always trying. >>> >>> Upon examination it turns out part of the problem is actually most of >>> the solution. Since 2.5 signal delivery has found all fatal signals, >>> marked the signal group for death, and queued SIGKILL in every threads >>> thread queue relying on signal->group_exit_code to preserve the >>> information of which was the actual fatal signal. >>> >>> The conversion of all fatal signals to SIGKILL results in the >>> synchronous signal heuristic in next_signal kicking in and preferring >>> SIGHUP to SIGKILL. Which is especially problematic as all >>> fatal signals have already been transformed into SIGKILL. >>> >>> Instead of dequeueing signals and depending upon SIGKILL to >>> be the first signal dequeued, first test if the signal group >>> has already been marked for death. This guarantees that >>> nothing in the signal queue can prevent a process that needs >>> to exit from exiting. >>> >>> Cc: stable@vger.kernel.org >>> Tested-by: Dmitry Vyukov >>> Reported-by: Dmitry Vyukov >>> Ref: ebf5ebe31d2c ("[PATCH] signal-fixes-2.5.59-A4") >>> History Tree: https://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git >>> Signed-off-by: "Eric W. Biederman" >>> Signed-off-by: Greg Kroah-Hartman >> >> This patch breaks strace self-tests in 4.20.9. In particular, >> "threads-execve": >> https://github.com/strace/strace/blob/master/tests/threads-execve.c >> https://github.com/strace/strace/blob/master/tests/threads-execve.test >> >> The test received some fix a day ago, but it did not help in this case: >> https://github.com/strace/strace/commit/2a50278b9 >> >> Only a revert of the above patch helped. >> >> I don't know if the strace's test is broken (which is quite usual in >> cases like these) or the patch affects some user-visible behaviour -- >> e.g. could this be a reason for sh failures in the build farm? >> >> Any ideas? > > Does cf43a757fd49 ("signal: Restore the stop PTRACE_EVENT_EXIT") help > with this? It's queued up for the next round of stable releases and is > in Linus's tree. Yes, confirmed. thanks, -- js