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=-2.4 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,USER_AGENT_SANE_1 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 5C958C33C9E for ; Tue, 28 Jan 2020 11:48:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 29AE624687 for ; Tue, 28 Jan 2020 11:48:35 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="iXjK0EpU" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726254AbgA1Lse (ORCPT ); Tue, 28 Jan 2020 06:48:34 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:58981 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1725959AbgA1Lsd (ORCPT ); Tue, 28 Jan 2020 06:48:33 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1580212112; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=lz7R+vtlTh6RBBwj0e/+jD30ITTxMxb0pWI2woJxCN4=; b=iXjK0EpUFLJbFcE55x3mbfbnjLLXQtocwKSWSYhlY8It3ijHFQkPYotuFa8ipLHnqnvan4 eQ/bciTlsFBtSJRiTR0kvbJHBaKtJU6Ky39LylENhcAteUgwhM9rjD2qIJ0c4hbmEXcxLo 1jMg/mLL1FB/toLRQ3yKq1jOCFHyk/c= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-389-UsiETWpOOCi5duRfEJ096Q-1; Tue, 28 Jan 2020 06:48:24 -0500 X-MC-Unique: UsiETWpOOCi5duRfEJ096Q-1 Received: from smtp.corp.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 949F0107ACC4; Tue, 28 Jan 2020 11:48:22 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.43.17.70]) by smtp.corp.redhat.com (Postfix) with SMTP id 3FDA788828; Tue, 28 Jan 2020 11:48:20 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Tue, 28 Jan 2020 12:48:21 +0100 (CET) Date: Tue, 28 Jan 2020 12:48:18 +0100 From: Oleg Nesterov To: Jann Horn Cc: Amol Grover , David Howells , Shakeel Butt , James Morris , Kees Cook , Thomas Gleixner , kernel list , linux-kernel-mentees@lists.linuxfoundation.org, Joel Fernandes , Madhuparna Bhowmik , "Paul E . McKenney" Subject: Re: [PATCH] cred: Use RCU primitives to access RCU pointers Message-ID: <20200128114818.GA17943@redhat.com> References: <20200128072740.21272-1-frextrite@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.11 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/28, Jann Horn wrote: > > On Tue, Jan 28, 2020 at 8:28 AM Amol Grover wrote: > > task_struct.cred and task_struct.real_cred are annotated by __rcu, > > task_struct.cred doesn't actually have RCU semantics though, see > commit d7852fbd0f0423937fa287a598bfde188bb68c22. For task_struct.cred, > it would probably be more correct to remove the __rcu annotation? Yes, but get_task_cred() assumes it has RCU semantics... To be honest I didn't know we have this helper. Can't it race with revert_creds() in do_faccessat() ? Oleg.