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=-3.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 C5E28C48BCF for ; Sat, 12 Jun 2021 19:49:31 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 99B4C61029 for ; Sat, 12 Jun 2021 19:49:31 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230382AbhFLTtw (ORCPT ); Sat, 12 Jun 2021 15:49:52 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:58004 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229753AbhFLTts (ORCPT ); Sat, 12 Jun 2021 15:49:48 -0400 Received: from in02.mta.xmission.com ([166.70.13.52]) by out01.mta.xmission.com with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1ls9bd-00B7yK-Dq; Sat, 12 Jun 2021 13:47:45 -0600 Received: from ip68-227-160-95.om.om.cox.net ([68.227.160.95] helo=email.xmission.com) by in02.mta.xmission.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1ls9ba-00839m-4V; Sat, 12 Jun 2021 13:47:44 -0600 From: ebiederm@xmission.com (Eric W. Biederman) To: Andrew Morton Cc: Bernd Edlinger , Alexander Viro , Alexey Dobriyan , Oleg Nesterov , Kees Cook , Andy Lutomirski , Will Drewry , Shuah Khan , Christian Brauner , Michal Hocko , Serge Hallyn , James Morris , Charles Haithcock , Suren Baghdasaryan , Yafang Shao , Helge Deller , YiFei Zhu , Adrian Reber , Thomas Gleixner , Jens Axboe , "linux-fsdevel\@vger.kernel.org" , "linux-kernel\@vger.kernel.org" , linux-kselftest@vger.kernel.org References: <20210610143642.e4535dbdc0db0b1bd3ee5367@linux-foundation.org> Date: Sat, 12 Jun 2021 14:44:05 -0500 In-Reply-To: <20210610143642.e4535dbdc0db0b1bd3ee5367@linux-foundation.org> (Andrew Morton's message of "Thu, 10 Jun 2021 14:36:42 -0700") Message-ID: <87eed6zx4q.fsf@disp2133> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1ls9ba-00839m-4V;;;mid=<87eed6zx4q.fsf@disp2133>;;;hst=in02.mta.xmission.com;;;ip=68.227.160.95;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1+Lb/nnF3A2u0YB7jYNPcnJEbfzC5VPB3M= X-SA-Exim-Connect-IP: 68.227.160.95 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: Re: [PATCHv8] exec: Fix dead-lock in de_thread with ptrace_attach X-SA-Exim-Version: 4.2.1 (built Sat, 08 Feb 2020 21:53:50 +0000) X-SA-Exim-Scanned: Yes (on in02.mta.xmission.com) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton writes: > On Thu, 10 Jun 2021 09:31:42 +0200 Bernd Edlinger wrote: > >> This introduces signal->unsafe_execve_in_progress, >> which is used to fix the case when at least one of the >> sibling threads is traced, and therefore the trace >> process may dead-lock in ptrace_attach, but de_thread >> will need to wait for the tracer to continue execution. > > Deadlocks are serious. Is this exploitable by unprivileged userspace? The processes are killable so I don't think this is the serious in the way you mean. In fact Linus has already said that it is not a deadlock. Eric