Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753657AbaA0NpI (ORCPT ); Mon, 27 Jan 2014 08:45:08 -0500 Received: from relay.parallels.com ([195.214.232.42]:55662 "EHLO relay.parallels.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753138AbaA0NpE (ORCPT ); Mon, 27 Jan 2014 08:45:04 -0500 Date: Mon, 27 Jan 2014 17:44:54 +0400 From: Andrew Vagin To: Andrey Vagin CC: , Eric Dumazet , , , , , , Florian Westphal , Cyrill Gorcunov , Vasiliy Averin Subject: Re: [PATCH] [RFC] netfilter: nf_conntrack: don't relase a conntrack with non-zero refcnt Message-ID: <20140127134453.GA26336@paralelels.com> References: <1389710201.31367.255.camel@edumazet-glaptop2.roam.corp.google.com> <1389720948-7883-1-git-send-email-avagin@openvz.org> MIME-Version: 1.0 Content-Type: text/plain; charset="koi8-r" Content-Disposition: inline In-Reply-To: <1389720948-7883-1-git-send-email-avagin@openvz.org> User-Agent: Mutt/1.5.21 (2010-09-15) X-Originating-IP: [10.30.16.48] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Jan 14, 2014 at 09:35:48PM +0400, Andrey Vagin wrote: > ---- > Eric and Florian, could you look at this patch. When you say, > that it looks good, I will ask the user to validate it. > I can't reorder these actions, because it's reproduced on a real host > with real users. Thanks. We didn't get new reports from users for the last week, so these patches fix the problem. > ---- > > nf_conntrack_free can't be called for a conntract with non-zero ref-counter, > because it can race with nf_conntrack_find_get(). > > A conntrack slab is created with SLAB_DESTROY_BY_RCU. Non-zero > ref-conunter says that this conntrack is used now. So when we release a > conntrack with non-zero counter, we break this assumption. > > CPU1 CPU2 > ____nf_conntrack_find() > nf_ct_put() > destroy_conntrack() > ... > init_conntrack > __nf_conntrack_alloc (set use = 1) > atomic_inc_not_zero(&ct->use) (use = 2) > if (!l4proto->new(ct, skb, dataoff, timeouts)) > nf_conntrack_free(ct); (use = 2 !!!) > ... > __nf_conntrack_alloc (set use = 1) > if (!nf_ct_key_equal(h, tuple, zone)) > nf_ct_put(ct); (use = 0) > destroy_conntrack() > /* continue to work with CT */ > > After applying the path "[PATCH] netfilter: nf_conntrack: fix RCU race > in nf_conntrack_find_get (v3)" another bug was triggered in > destroy_conntrack(): > <4>[67096.759334] ------------[ cut here ]------------ > <2>[67096.759353] kernel BUG at net/netfilter/nf_conntrack_core.c:211! > ... > <4>[67096.759837] Pid: 498649, comm: atdd veid: 666 Tainted: G C --------------- 2.6.32-042stab084.18 #1 042stab084_18 /DQ45CB > <4>[67096.759932] RIP: 0010:[] [] destroy_conntrack+0x15c/0x190 [nf_conntrack] > <4>[67096.760255] Call Trace: > <4>[67096.760255] [] nf_conntrack_destroy+0x17/0x30 > <4>[67096.760255] [] nf_conntrack_find_get+0x85/0x130 [nf_conntrack] > <4>[67096.760255] [] nf_conntrack_in+0x352/0xb60 [nf_conntrack] > <4>[67096.760255] [] ipv4_conntrack_local+0x51/0x60 [nf_conntrack_ipv4] > <4>[67096.760255] [] nf_iterate+0x69/0xb0 > <4>[67096.760255] [] ? dst_output+0x0/0x20 > <4>[67096.760255] [] nf_hook_slow+0x74/0x110 > <4>[67096.760255] [] ? dst_output+0x0/0x20 > <4>[67096.760255] [] raw_sendmsg+0x775/0x910 > <4>[67096.760255] [] ? flush_tlb_others_ipi+0x128/0x130 > <4>[67096.760255] [] ? apic_timer_interrupt+0xe/0x20 > <4>[67096.760255] [] ? apic_timer_interrupt+0xe/0x20 > <4>[67096.760255] [] inet_sendmsg+0x4a/0xb0 > <4>[67096.760255] [] ? sock_sendmsg+0x13/0x140 > <4>[67096.760255] [] sock_sendmsg+0x117/0x140 > <4>[67096.760255] [] ? native_smp_send_reschedule+0x49/0x60 > <4>[67096.760255] [] ? _spin_unlock_bh+0x1b/0x20 > <4>[67096.760255] [] ? autoremove_wake_function+0x0/0x40 > <4>[67096.760255] [] ? do_ip_setsockopt+0x90/0xd80 > <4>[67096.760255] [] ? apic_timer_interrupt+0xe/0x20 > <4>[67096.760255] [] ? apic_timer_interrupt+0xe/0x20 > <4>[67096.760255] [] sys_sendto+0x139/0x190 > <4>[67096.760255] [] ? audit_syscall_entry+0x1d7/0x200 > <4>[67096.760255] [] ? __audit_syscall_exit+0x265/0x290 > <4>[67096.760255] [] compat_sys_socketcall+0x13f/0x210 > <4>[67096.760255] [] ia32_sysret+0x0/0x5 > > Cc: Eric Dumazet > Cc: Florian Westphal > Cc: Cyrill Gorcunov > Cc: Vasiliy Averin > Signed-off-by: Andrey Vagin > --- > include/net/netfilter/nf_conntrack.h | 1 - > net/netfilter/nf_conntrack_core.c | 18 +++++++++++------- > net/netfilter/nf_conntrack_netlink.c | 2 +- > net/netfilter/nf_synproxy_core.c | 4 ++-- > net/netfilter/xt_CT.c | 2 +- > 5 files changed, 15 insertions(+), 12 deletions(-) > > diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h > index 01ea6ee..d338316 100644 > --- a/include/net/netfilter/nf_conntrack.h > +++ b/include/net/netfilter/nf_conntrack.h > @@ -243,7 +243,6 @@ void nf_ct_untracked_status_or(unsigned long bits); > void nf_ct_iterate_cleanup(struct net *net, > int (*iter)(struct nf_conn *i, void *data), > void *data, u32 portid, int report); > -void nf_conntrack_free(struct nf_conn *ct); > struct nf_conn *nf_conntrack_alloc(struct net *net, u16 zone, > const struct nf_conntrack_tuple *orig, > const struct nf_conntrack_tuple *repl, > diff --git a/net/netfilter/nf_conntrack_core.c b/net/netfilter/nf_conntrack_core.c > index b56e53b..c38cc74 100644 > --- a/net/netfilter/nf_conntrack_core.c > +++ b/net/netfilter/nf_conntrack_core.c > @@ -198,6 +198,8 @@ clean_from_lists(struct nf_conn *ct) > nf_ct_remove_expectations(ct); > } > > +static void nf_conntrack_free(struct nf_conn *ct); > + > static void > destroy_conntrack(struct nf_conntrack *nfct) > { > @@ -226,9 +228,8 @@ destroy_conntrack(struct nf_conntrack *nfct) > * too. */ > nf_ct_remove_expectations(ct); > > - /* We overload first tuple to link into unconfirmed or dying list.*/ > - BUG_ON(hlist_nulls_unhashed(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode)); > - hlist_nulls_del_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode); > + if (!hlist_nulls_unhashed(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode)) > + hlist_nulls_del_rcu(&ct->tuplehash[IP_CT_DIR_ORIGINAL].hnnode); > > NF_CT_STAT_INC(net, delete); > spin_unlock_bh(&nf_conntrack_lock); > @@ -772,18 +773,21 @@ struct nf_conn *nf_conntrack_alloc(struct net *net, u16 zone, > } > EXPORT_SYMBOL_GPL(nf_conntrack_alloc); > > -void nf_conntrack_free(struct nf_conn *ct) > +static void nf_conntrack_free(struct nf_conn *ct) > { > struct net *net = nf_ct_net(ct); > > + /* A freed object has refcnt == 0, thats > + * the golden rule for SLAB_DESTROY_BY_RCU > + */ > + NF_CT_ASSERT(atomic_read(&ct->ct_general.use) == 0); > + > nf_ct_ext_destroy(ct); > nf_ct_ext_free(ct); > kmem_cache_free(net->ct.nf_conntrack_cachep, ct); > smp_mb__before_atomic_dec(); > atomic_dec(&net->ct.count); > } > -EXPORT_SYMBOL_GPL(nf_conntrack_free); > - > > /* Allocate a new conntrack: we return -ENOMEM if classification > failed due to stress. Otherwise it really is unclassifiable. */ > @@ -835,7 +839,7 @@ init_conntrack(struct net *net, struct nf_conn *tmpl, > } > > if (!l4proto->new(ct, skb, dataoff, timeouts)) { > - nf_conntrack_free(ct); > + nf_ct_put(ct); > pr_debug("init conntrack: can't track with proto module\n"); > return NULL; > } > diff --git a/net/netfilter/nf_conntrack_netlink.c b/net/netfilter/nf_conntrack_netlink.c > index 3e91ad3..fadd0f3 100644 > --- a/net/netfilter/nf_conntrack_netlink.c > +++ b/net/netfilter/nf_conntrack_netlink.c > @@ -1732,7 +1732,7 @@ ctnetlink_create_conntrack(struct net *net, u16 zone, > err2: > rcu_read_unlock(); > err1: > - nf_conntrack_free(ct); > + nf_ct_put(ct); > return ERR_PTR(err); > } > > diff --git a/net/netfilter/nf_synproxy_core.c b/net/netfilter/nf_synproxy_core.c > index 9858e3e..d12234c 100644 > --- a/net/netfilter/nf_synproxy_core.c > +++ b/net/netfilter/nf_synproxy_core.c > @@ -381,7 +381,7 @@ static int __net_init synproxy_net_init(struct net *net) > err3: > free_percpu(snet->stats); > err2: > - nf_conntrack_free(ct); > + nf_ct_put(ct); > err1: > return err; > } > @@ -390,7 +390,7 @@ static void __net_exit synproxy_net_exit(struct net *net) > { > struct synproxy_net *snet = synproxy_pernet(net); > > - nf_conntrack_free(snet->tmpl); > + nf_ct_put(snet->tmpl); > synproxy_proc_exit(net); > free_percpu(snet->stats); > } > diff --git a/net/netfilter/xt_CT.c b/net/netfilter/xt_CT.c > index da35ac0..da4edfe 100644 > --- a/net/netfilter/xt_CT.c > +++ b/net/netfilter/xt_CT.c > @@ -237,7 +237,7 @@ out: > return 0; > > err3: > - nf_conntrack_free(ct); > + nf_ct_put(ct); > err2: > nf_ct_l3proto_module_put(par->family); > err1: > -- > 1.8.4.2 > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/