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=-7.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS 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 D5B67C4360F for ; Wed, 20 Mar 2019 14:01:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AFBAD2184D for ; Wed, 20 Mar 2019 14:01:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728237AbfCTOBc (ORCPT ); Wed, 20 Mar 2019 10:01:32 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45976 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727428AbfCTOBb (ORCPT ); Wed, 20 Mar 2019 10:01:31 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 9AEBE83F42; Wed, 20 Mar 2019 14:01:31 +0000 (UTC) Received: from new-host.redhat.com (ovpn-204-166.brq.redhat.com [10.40.204.166]) by smtp.corp.redhat.com (Postfix) with ESMTP id B3EB02633A; Wed, 20 Mar 2019 14:01:29 +0000 (UTC) From: Davide Caratti To: Cong Wang , Vlad Buslov , Jamal Hadi Salim , Jiri Pirko , "David S . Miller" , netdev Cc: Paolo Abeni Subject: [PATCH net v2 17/18] net/sched: don't dereference a->goto_chain to read the chain index Date: Wed, 20 Mar 2019 15:00:15 +0100 Message-Id: <1f64c8daa2a98f0808d7f834013cb36fe2eb2bff.1553085664.git.dcaratti@redhat.com> In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Wed, 20 Mar 2019 14:01:31 +0000 (UTC) Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org callers of tcf_gact_goto_chain_index() can potentially read an old value of the chain index, or even dereference a NULL 'goto_chain' pointer, because 'goto_chain' and 'tcfa_action' are read in the traffic path without caring of concurrent write in the control path. The most recent value of chain index can be read also from a->tcfa_action (it's encoded there together with TC_ACT_GOTO_CHAIN bits), so we don't really need to dereference 'goto_chain': just read the chain id from the control action. Fixes: e457d86ada27 ("net: sched: add couple of goto_chain helpers") Signed-off-by: Davide Caratti --- include/net/tc_act/tc_gact.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/net/tc_act/tc_gact.h b/include/net/tc_act/tc_gact.h index ee8d005f56fc..eb8f01c819e6 100644 --- a/include/net/tc_act/tc_gact.h +++ b/include/net/tc_act/tc_gact.h @@ -56,7 +56,7 @@ static inline bool is_tcf_gact_goto_chain(const struct tc_action *a) static inline u32 tcf_gact_goto_chain_index(const struct tc_action *a) { - return a->goto_chain->index; + return READ_ONCE(a->tcfa_action) & TC_ACT_EXT_VAL_MASK; } #endif /* __NET_TC_GACT_H */ -- 2.20.1