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=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,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 EDF40C433E0 for ; Fri, 15 May 2020 01:01:35 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D562C2065F for ; Fri, 15 May 2020 01:01:35 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728679AbgEOBBe (ORCPT ); Thu, 14 May 2020 21:01:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49536 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-FAIL-OK-FAIL) by vger.kernel.org with ESMTP id S1726170AbgEOBBd (ORCPT ); Thu, 14 May 2020 21:01:33 -0400 Received: from shards.monkeyblade.net (shards.monkeyblade.net [IPv6:2620:137:e000::1:9]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id BE4FCC061A0C; Thu, 14 May 2020 18:01:33 -0700 (PDT) Received: from localhost (unknown [IPv6:2601:601:9f00:477::3d5]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id CA3CD14DD553C; Thu, 14 May 2020 18:01:32 -0700 (PDT) Date: Thu, 14 May 2020 18:01:32 -0700 (PDT) Message-Id: <20200514.180132.1153550322947224128.davem@davemloft.net> To: frextrite@gmail.com Cc: kuznet@ms2.inr.ac.ru, yoshfuji@linux-ipv6.org, kuba@kernel.org, kaber@trash.net, sfr@canb.auug.org.au, cai@lca.pw, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, joel@joelfernandes.org, madhuparnabhowmik10@gmail.com, paulmck@kernel.org, syzbot+1519f497f2f9f08183c6@syzkaller.appspotmail.com Subject: Re: [PATCH net v2 2/2] ipmr: Add lockdep expression to ipmr_for_each_table macro From: David Miller In-Reply-To: <20200514180102.26425-2-frextrite@gmail.com> References: <20200514180102.26425-1-frextrite@gmail.com> <20200514180102.26425-2-frextrite@gmail.com> X-Mailer: Mew version 6.8 on Emacs 26.3 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Thu, 14 May 2020 18:01:33 -0700 (PDT) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org From: Amol Grover Date: Thu, 14 May 2020 23:31:03 +0530 > During the initialization process, ipmr_new_table() is called > to create new tables which in turn calls ipmr_get_table() which > traverses net->ipv4.mr_tables without holding the writer lock. > However, this is safe to do so as no tables exist at this time. > Hence add a suitable lockdep expression to silence the following > false-positive warning: > > ============================= > WARNING: suspicious RCU usage > 5.7.0-rc3-next-20200428-syzkaller #0 Not tainted > ----------------------------- > net/ipv4/ipmr.c:136 RCU-list traversed in non-reader section!! > > ipmr_get_table+0x130/0x160 net/ipv4/ipmr.c:136 > ipmr_new_table net/ipv4/ipmr.c:403 [inline] > ipmr_rules_init net/ipv4/ipmr.c:248 [inline] > ipmr_net_init+0x133/0x430 net/ipv4/ipmr.c:3089 > > Fixes: f0ad0860d01e ("ipv4: ipmr: support multiple tables") > Reported-by: syzbot+1519f497f2f9f08183c6@syzkaller.appspotmail.com > Suggested-by: Jakub Kicinski > Signed-off-by: Amol Grover Applied.