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=-0.8 required=3.0 tests=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 D65C5FA3728 for ; Wed, 16 Oct 2019 23:24:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B26302168B for ; Wed, 16 Oct 2019 23:24:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390299AbfJPXYi (ORCPT ); Wed, 16 Oct 2019 19:24:38 -0400 Received: from mx1.redhat.com ([209.132.183.28]:47574 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725970AbfJPXYi (ORCPT ); Wed, 16 Oct 2019 19:24:38 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 685F28535C; Wed, 16 Oct 2019 23:24:38 +0000 (UTC) Received: from warthog.procyon.org.uk (ovpn-121-84.rdu2.redhat.com [10.10.121.84]) by smtp.corp.redhat.com (Postfix) with ESMTP id 2F62210013A1; Wed, 16 Oct 2019 23:24:37 +0000 (UTC) Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 From: David Howells In-Reply-To: <20191014130438.163688-1-edumazet@google.com> References: <20191014130438.163688-1-edumazet@google.com> To: Eric Dumazet Cc: dhowells@redhat.com, "David S . Miller" , netdev , Eric Dumazet , Jakub Kicinski Subject: Re: [PATCH net] rxrpc: use rcu protection while reading sk->sk_user_data MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-ID: <8141.1571268276.1@warthog.procyon.org.uk> Date: Thu, 17 Oct 2019 00:24:36 +0100 Message-ID: <8142.1571268276@warthog.procyon.org.uk> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.25]); Wed, 16 Oct 2019 23:24:38 +0000 (UTC) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Eric Dumazet wrote: > We need to extend the rcu_read_lock() section in rxrpc_error_report() > and use rcu_dereference_sk_user_data() instead of plain access > to sk->sk_user_data to make sure all rules are respected. Should I take it that the caller won't be guaranteed to be holding the RCU read lock? Looking at __udp4_lib_err(), that calls __udp4_lib_err_encap(), which calls __udp4_lib_err_encap_no_sk(), which should throw a warning if the RCU read lock is not held. Similarly, icmp_socket_deliver() and icmpv6_notify() should also throw a warning before calling ->err_handler(). Does that mean something further up the CPU stack is going to be holding the RCU read lock? David