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=-3.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_PASS, USER_AGENT_NEOMUTT autolearn=ham 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 BABADC10F0E for ; Thu, 18 Apr 2019 09:36:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 85DBD21850 for ; Thu, 18 Apr 2019 09:36:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=brauner.io header.i=@brauner.io header.b="NXKztfCO" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2388490AbfDRJge (ORCPT ); Thu, 18 Apr 2019 05:36:34 -0400 Received: from mail-ed1-f68.google.com ([209.85.208.68]:35184 "EHLO mail-ed1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2388044AbfDRJge (ORCPT ); Thu, 18 Apr 2019 05:36:34 -0400 Received: by mail-ed1-f68.google.com with SMTP id y67so1261180ede.2 for ; Thu, 18 Apr 2019 02:36:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=brauner.io; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=RUWum+Va8Z//jAipbx3o13SVsAv8KB7rFp2TRt5t/Rk=; b=NXKztfCOd+fSDtYoQU4LaNKH1DHMz1g4gjQzMKGYNYydsfBFvXQprtejqnEnHHWozb CMd6gjnvuks+QCuYwswWjoB8aeGsWR7ekrDUwHSMTcTqNqzVSIjttJl0Gtb1uppfwTd7 NoD3NECnl5rnr7LfU7KQaJtHcgMTZ10pARYGjwzBG/aIQeMSdV0kXNM3XDSXMaZH8t33 8gXk+YFniNWR8t7pvumroZPUXzbmEI29fNoLVwSuA5eYmk+7M0AmG2q893mvYR/Gjsa2 HtkGEJZBHGTkwirfAPS73hY5BF0pDHeokRR/spU902DbN7/w6xZyqsd8uj5B6R+cu/xB E/CA== 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:user-agent; bh=RUWum+Va8Z//jAipbx3o13SVsAv8KB7rFp2TRt5t/Rk=; b=NpucbfmmHQzWUsW3IMtJjs0n4eWhq+bCumRBJGrkLK5dukfm6uNdZQJKa35omfihto XCewrpGWWr+JPS/nL/NPX/XWO/QHWKHcpPDAtbw/Bfk1lM3kO2YqW+fRhk520ZUPmgxU Ez1WtS/G0RZcwlgR+7ucbNd0osUzxzTS2VeVxlyXmpXcGBAi2rG0cNMO4qW0bgPQ7pl7 LYCknnCiLBu2N5CTlO2NiW98r6xFsfyk4msq/EVS2GHA5/cg6B4YhZHYD5MYD17RIhwd 8rvza9NTDIIUVG5ljJDp490mSKIv+kzTb6e9kHbJVWMfA8hVFN+P/NROvhmLslXNzBxY EzaA== X-Gm-Message-State: APjAAAWLYJLwLv9pvKQUZgfeX/iyTW38PvvJmTTG7GrZBHQuU30J+dUB 6IRcQ8Y+ndvXN4vTrKzcJ7S3Vg== X-Google-Smtp-Source: APXvYqwPPEGctDAmToWSMGLAevSWwbrCqU+Xxdc7DcxOzpI59beah5B5o6Mt4CKANjYas/+0ICbc0g== X-Received: by 2002:a50:f5a2:: with SMTP id u31mr24357976edm.166.1555580192182; Thu, 18 Apr 2019 02:36:32 -0700 (PDT) Received: from brauner.io ([212.91.227.56]) by smtp.gmail.com with ESMTPSA id j18sm379039edj.92.2019.04.18.02.36.30 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Thu, 18 Apr 2019 02:36:31 -0700 (PDT) Date: Thu, 18 Apr 2019 11:36:30 +0200 From: Christian Brauner To: Oleg Nesterov Cc: torvalds@linux-foundation.org, viro@zeniv.linux.org.uk, jannh@google.com, dhowells@redhat.com, linux-api@vger.kernel.org, linux-kernel@vger.kernel.org, serge@hallyn.com, luto@kernel.org, arnd@arndb.de, ebiederm@xmission.com, keescook@chromium.org, tglx@linutronix.de, mtk.manpages@gmail.com, akpm@linux-foundation.org, cyphar@cyphar.com, joel@joelfernandes.org, dancol@google.com Subject: Re: [PATCH v1 2/4] clone: add CLONE_PIDFD Message-ID: <20190418093629.6fshxhambc2zzjdk@brauner.io> References: <20190416170233.10208-1-christian@brauner.io> <20190416170233.10208-3-christian@brauner.io> <20190417142253.GH32622@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20190417142253.GH32622@redhat.com> User-Agent: NeoMutt/20180716 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Apr 17, 2019 at 04:22:54PM +0200, Oleg Nesterov wrote: > On 04/16, Christian Brauner wrote: > > > > + if (clone_flags & CLONE_PIDFD) { > > + retval = pidfd_create(pid, &pidfdf); > > + if (retval < 0) > > + goto bad_fork_free_pid; > > + pidfd = retval; > > + } > > ... > > > + if (clone_flags & CLONE_PIDFD) { > > + fd_install(pidfd, pidfdf); > > + put_user(pidfd, parent_tidptr); > > put_user() can fail, I don't think this error should be silently ignored, > this can lead to the hard-to-trigger/debug problems. > > Why can't we do put_user-with-check along with pidfd_create() above? I've moved put_user() right were pidfd_create() is called but I think then it makes sense to change pidfd_create() to also do the fd_install() such that the following sequence creates the pidfd, installs it, and calls put_user() and calls ksys_close() on error. Any objections Oleg? + if (clone_flags & CLONE_PIDFD) { + retval = pidfd_create(pid); + if (retval < 0) + goto bad_fork_free_pid; + + pidfd = retval; + retval = put_user(pidfd, parent_tidptr); + if (retval) + goto bad_fork_put_pidfd; + } Christian