From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:54678 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727586AbfBYVGE (ORCPT ); Mon, 25 Feb 2019 16:06:04 -0500 Received: from pps.filterd (m0098404.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.27/8.16.0.27) with SMTP id x1PL4q4M104778 for ; Mon, 25 Feb 2019 16:06:03 -0500 Received: from e16.ny.us.ibm.com (e16.ny.us.ibm.com [129.33.205.206]) by mx0a-001b2d01.pphosted.com with ESMTP id 2qvncy7pmx-1 (version=TLSv1.2 cipher=AES256-GCM-SHA384 bits=256 verify=NOT) for ; Mon, 25 Feb 2019 16:06:03 -0500 Received: from localhost by e16.ny.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 25 Feb 2019 21:06:01 -0000 Date: Mon, 25 Feb 2019 13:05:51 -0800 From: "Paul E. McKenney" Subject: Re: [PATCH v2 1/6] net: rtnetlink: Fix incorrect RCU API usage Reply-To: paulmck@linux.ibm.com References: <20190223063434.6793-1-joel@joelfernandes.org> <20190223063434.6793-2-joel@joelfernandes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190223063434.6793-2-joel@joelfernandes.org> Message-Id: <20190225210551.GV4072@linux.ibm.com> Sender: xdp-newbies-owner@vger.kernel.org List-ID: To: "Joel Fernandes (Google)" Cc: linux-kernel@vger.kernel.org, Alexei Starovoitov , Christian Brauner , Daniel Borkmann , David Ahern , "David S. Miller" , Ingo Molnar , Jakub Kicinski , Jeff Kirsher , Jesper Dangaard Brouer , John Fastabend , Josh Triplett , keescook@chromium.org, kernel-hardening@lists.openwall.com, kernel-team@android.com, Kirill Tkhai , Lai Jiangshan , Martin KaFai Lau , Mathieu Desnoyers , netdev@vger.kernel.org, Peter Zijlstra , Quentin Perret , rcu@vger.kernel.org, Song Liu , Steven Rostedt , Vincent Guittot , xdp-newbies@vger.kernel.org, Yonghong Song On Sat, Feb 23, 2019 at 01:34:29AM -0500, Joel Fernandes (Google) wrote: > rtnl_register_internal() and rtnl_unregister_all tries to directly > dereference an RCU protected pointed outside RCU read side section. > While this is Ok to do since a lock is held, let us use the correct > API to avoid programmer bugs in the future. > > This also fixes sparse warnings arising from not using RCU API. > > net/core/rtnetlink.c:332:13: warning: incorrect type in assignment > (different address spaces) net/core/rtnetlink.c:332:13: expected > struct rtnl_link **tab net/core/rtnetlink.c:332:13: got struct > rtnl_link *[noderef] * > > Signed-off-by: Joel Fernandes (Google) >From an RCU perspective: Reviewed-by: Paul E. McKenney > --- > net/core/rtnetlink.c | 4 ++-- > 1 file changed, 2 insertions(+), 2 deletions(-) > > diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c > index 5ea1bed08ede..98be4b4818a9 100644 > --- a/net/core/rtnetlink.c > +++ b/net/core/rtnetlink.c > @@ -188,7 +188,7 @@ static int rtnl_register_internal(struct module *owner, > msgindex = rtm_msgindex(msgtype); > > rtnl_lock(); > - tab = rtnl_msg_handlers[protocol]; > + tab = rtnl_dereference(rtnl_msg_handlers[protocol]); > if (tab == NULL) { > tab = kcalloc(RTM_NR_MSGTYPES, sizeof(void *), GFP_KERNEL); > if (!tab) > @@ -329,7 +329,7 @@ void rtnl_unregister_all(int protocol) > BUG_ON(protocol < 0 || protocol > RTNL_FAMILY_MAX); > > rtnl_lock(); > - tab = rtnl_msg_handlers[protocol]; > + tab = rtnl_dereference(rtnl_msg_handlers[protocol]); > if (!tab) { > rtnl_unlock(); > return; > -- > 2.21.0.rc0.258.g878e2cd30e-goog >