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=-0.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 205B2C10F27 for ; Tue, 10 Mar 2020 20:47:56 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id C3D992253D for ; Tue, 10 Mar 2020 20:47:55 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=chromium.org header.i=@chromium.org header.b="fMgZFq3z" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C3D992253D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=chromium.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 6F2C66B0003; Tue, 10 Mar 2020 16:47:55 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 6545D6B0006; Tue, 10 Mar 2020 16:47:55 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 4F6066B0007; Tue, 10 Mar 2020 16:47:55 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0076.hostedemail.com [216.40.44.76]) by kanga.kvack.org (Postfix) with ESMTP id 33D916B0003 for ; Tue, 10 Mar 2020 16:47:55 -0400 (EDT) Received: from smtpin12.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 045E3180AD802 for ; Tue, 10 Mar 2020 20:47:55 +0000 (UTC) X-FDA: 76580639310.12.angle56_27f8c26692418 X-HE-Tag: angle56_27f8c26692418 X-Filterd-Recvd-Size: 5383 Received: from mail-pj1-f65.google.com (mail-pj1-f65.google.com [209.85.216.65]) by imf24.hostedemail.com (Postfix) with ESMTP for ; Tue, 10 Mar 2020 20:47:54 +0000 (UTC) Received: by mail-pj1-f65.google.com with SMTP id a16so943419pju.3 for ; Tue, 10 Mar 2020 13:47:54 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=DUcwxxFRcgJR1d4ydhPOJt5zpra6K7hoDMr6GJuC66g=; b=fMgZFq3zdtsmjgrmZ83y+dSJSkDsZ1RxXFLnaUXLAWftyCsRbpnOPIZELEJvQYB2uH DCaJNkF/BmiZuR2IY7of7B5eWU3CYM1Bp+RKbcTdNqEPhwk3h5BL4rLBDUiAP20fc1Ps c+5viBYTEXQxtAUajXiZWTdBthiDog7IGOpM4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to; bh=DUcwxxFRcgJR1d4ydhPOJt5zpra6K7hoDMr6GJuC66g=; b=suwOdXUUcSSr8x6CBmEvZzIVgfTle/A+bEPJtK4QG7cSoVmRp8pWEmHexnaOvoLCaW +t49YDocyoJR12/8S7TJYsRqVBOrrT/guhyBl6CvcLKVm4lKFHCn9+stw3l/A7Bjd3zu 521UZyNbOuOJvNERCLrPR9wjJfmBqrNxfoaXDooffJdXs+QcGQWzWFIKzhyAkTcH38L7 +QwGMvKpWNKpHYacLvskbNWQdAcn2QlM9/joJyJECVqUuQuFk/wcRCsrRTIg6F+2yV3B ZUpgwdlezPCwJA3E6iAlsAM1ZdbEySpM0TnDrH5HkdYr8GGge0mAB8uc2/JDZJy1RrK/ Qc/w== X-Gm-Message-State: ANhLgQ3PSykO7K/8ByAmAtOoC1XuG8uO9GTqLRp2sv3UYVRnT9SlgsdJ 0XIjbjaw5QXYXUhMaUzqs121Nw== X-Google-Smtp-Source: ADFU+vudklcF8vh1bAtfnAiwP2o2XGlvb6JQXVwHa2R6IlMHlYTM2ZG1kz9TwCHN7BvEtMrMXaoTKg== X-Received: by 2002:a17:902:bf0b:: with SMTP id bi11mr10776957plb.245.1583873273478; Tue, 10 Mar 2020 13:47:53 -0700 (PDT) Received: from www.outflux.net (smtp.outflux.net. [198.145.64.163]) by smtp.gmail.com with ESMTPSA id t6sm16907149pfb.172.2020.03.10.13.47.52 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 10 Mar 2020 13:47:52 -0700 (PDT) Date: Tue, 10 Mar 2020 13:47:51 -0700 From: Kees Cook To: "Eric W. Biederman" Cc: Bernd Edlinger , Christian Brauner , Jann Horn , Jonathan Corbet , Alexander Viro , Andrew Morton , Alexey Dobriyan , Thomas Gleixner , Oleg Nesterov , Frederic Weisbecker , Andrei Vagin , Ingo Molnar , "Peter Zijlstra (Intel)" , Yuyang Du , David Hildenbrand , Sebastian Andrzej Siewior , Anshuman Khandual , David Howells , James Morris , Greg Kroah-Hartman , Shakeel Butt , Jason Gunthorpe , Christian Kellner , Andrea Arcangeli , Aleksa Sarai , "Dmitry V. Levin" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" , "stable@vger.kernel.org" , "linux-api@vger.kernel.org" Subject: Re: [PATCH v2 4/5] exec: Move exec_mmap right after de_thread in flush_old_exec Message-ID: <202003101344.8777D43A44@keescook> References: <87v9nlii0b.fsf@x220.int.ebiederm.org> <87a74xi4kz.fsf@x220.int.ebiederm.org> <87r1y8dqqz.fsf@x220.int.ebiederm.org> <87tv32cxmf.fsf_-_@x220.int.ebiederm.org> <87v9ne5y4y.fsf_-_@x220.int.ebiederm.org> <875zfe5xzb.fsf_-_@x220.int.ebiederm.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <875zfe5xzb.fsf_-_@x220.int.ebiederm.org> X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Sun, Mar 08, 2020 at 04:38:00PM -0500, Eric W. Biederman wrote: > Futher this consolidates all of the possible indefinite waits for > userspace together at the top of flush_old_exec. The possible wait > for a ptracer on PTRACE_EVENT_EXIT, the possible wait for a page fault > to be resolved in clear_child_tid, and the possible wait for a page > fault in exit_robust_list. I forgot to mention, just as a point of clarity, there are lots of other page faults possible, but they're _before_ flush_old_exec() (i.e. all the copy_strings() calls). Is it worth clarifying this to "before or at the top of flush_old_exec()" or do you mean something else? (And as always: perhaps expand flush_old_exec()'s comment to describe the newly intended state.) -- Kees Cook