From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752673AbeEPHnh (ORCPT ); Wed, 16 May 2018 03:43:37 -0400 Received: from mail-wm0-f66.google.com ([74.125.82.66]:35934 "EHLO mail-wm0-f66.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752516AbeEPHne (ORCPT ); Wed, 16 May 2018 03:43:34 -0400 X-Google-Smtp-Source: AB8JxZoT/XFueLSNIyfKctGw/kg6+Lo3LrbkabTfRvjDM99wrAf9Dk6p7BUnFFub0pboUE4SdnhJrw== Date: Wed, 16 May 2018 09:43:32 +0200 From: Jiri Pirko To: Vlad Buslov Cc: netdev@vger.kernel.org, davem@davemloft.net, jhs@mojatatu.com, xiyou.wangcong@gmail.com, pablo@netfilter.org, kadlec@blackhole.kfki.hu, fw@strlen.de, ast@kernel.org, daniel@iogearbox.net, edumazet@google.com, keescook@chromium.org, linux-kernel@vger.kernel.org, netfilter-devel@vger.kernel.org, coreteam@netfilter.org, kliteyn@mellanox.com Subject: Re: [PATCH 09/14] net: sched: don't release reference on action overwrite Message-ID: <20180516074332.GB1972@nanopsycho> References: <1526308035-12484-1-git-send-email-vladbu@mellanox.com> <1526308035-12484-10-git-send-email-vladbu@mellanox.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1526308035-12484-10-git-send-email-vladbu@mellanox.com> User-Agent: Mutt/1.9.2 (2017-12-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Mon, May 14, 2018 at 04:27:10PM CEST, vladbu@mellanox.com wrote: >Return from action init function with reference to action taken, >even when overwriting existing action. > >Action init API initializes its fourth argument (pointer to pointer to >tc action) to either existing action with same index or newly created >action. In case of existing index(and bind argument is zero), init >function returns without incrementing action reference counter. Caller >of action init then proceeds working with action without actually >holding reference to it. This means that action could be deleted >concurrently. To prevent such scenario this patch changes action init Be imperative to the codebase in the patch description. >behavior to always take reference to action before returning >successfully. Where's the balance? Who does the release instead? I'm probably missing something. > >Signed-off-by: Vlad Buslov >--- > net/sched/act_bpf.c | 8 ++++---- > net/sched/act_connmark.c | 5 +++-- > net/sched/act_csum.c | 8 ++++---- > net/sched/act_gact.c | 5 +++-- > net/sched/act_ife.c | 12 +++++------- > net/sched/act_ipt.c | 5 +++-- > net/sched/act_mirred.c | 5 ++--- > net/sched/act_nat.c | 5 +++-- > net/sched/act_pedit.c | 5 +++-- > net/sched/act_police.c | 8 +++----- > net/sched/act_sample.c | 8 +++----- > net/sched/act_simple.c | 5 +++-- > net/sched/act_skbedit.c | 5 +++-- > net/sched/act_skbmod.c | 8 +++----- > net/sched/act_tunnel_key.c | 8 +++----- > net/sched/act_vlan.c | 8 +++----- > 16 files changed, 51 insertions(+), 57 deletions(-) > >diff --git a/net/sched/act_bpf.c b/net/sched/act_bpf.c >index 5d95c43..5554bf7 100644 >--- a/net/sched/act_bpf.c >+++ b/net/sched/act_bpf.c >@@ -311,9 +311,10 @@ static int tcf_bpf_init(struct net *net, struct nlattr *nla, > if (bind) > return 0; > >- tcf_idr_release(*act, bind); >- if (!replace) >+ if (!replace) { >+ tcf_idr_release(*act, bind); > return -EEXIST; >+ } > } > > is_bpf = tb[TCA_ACT_BPF_OPS_LEN] && tb[TCA_ACT_BPF_OPS]; [...]