netdev - [PATCH net] openvswitch: add nf_ct_is_confirmed check before assigning the helper

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Date:   Thu,  6 Oct 2022 15:45:02 -0400
From:   Xin Long <lucien.xin@...il.com>
To:     network dev <netdev@...r.kernel.org>, dev@...nvswitch.org
Cc:     davem@...emloft.net, kuba@...nel.org,
        Eric Dumazet <edumazet@...gle.com>,
        Paolo Abeni <pabeni@...hat.com>,
        Pravin B Shelar <pshelar@....org>,
        Florian Westphal <fw@...len.de>,
        Pablo Neira Ayuso <pablo@...filter.org>,
        Ilya Maximets <i.maximets@....org>,
        Eelco Chaudron <echaudro@...hat.com>,
        Yi-Hung Wei <yihung.wei@...il.com>
Subject: [PATCH net] openvswitch: add nf_ct_is_confirmed check before assigning the helper

A WARN_ON call trace would be triggered when 'ct(commit, alg=helper)'
applies on a confirmed connection:

  WARNING: CPU: 0 PID: 1251 at net/netfilter/nf_conntrack_extend.c:98
  RIP: 0010:nf_ct_ext_add+0x12d/0x150 [nf_conntrack]
  Call Trace:
   <TASK>
   nf_ct_helper_ext_add+0x12/0x60 [nf_conntrack]
   __nf_ct_try_assign_helper+0xc4/0x160 [nf_conntrack]
   __ovs_ct_lookup+0x72e/0x780 [openvswitch]
   ovs_ct_execute+0x1d8/0x920 [openvswitch]
   do_execute_actions+0x4e6/0xb60 [openvswitch]
   ovs_execute_actions+0x60/0x140 [openvswitch]
   ovs_packet_cmd_execute+0x2ad/0x310 [openvswitch]
   genl_family_rcv_msg_doit.isra.15+0x113/0x150
   genl_rcv_msg+0xef/0x1f0

which can be reproduced with these OVS flows:

  table=0, in_port=veth1,tcp,tcp_dst=2121,ct_state=-trk
  actions=ct(commit, table=1)
  table=1, in_port=veth1,tcp,tcp_dst=2121,ct_state=+trk+new
  actions=ct(commit, alg=ftp),normal

The issue was introduced by commit 248d45f1e193 ("openvswitch: Allow
attaching helper in later commit") where it somehow removed the check
of nf_ct_is_confirmed before asigning the helper. This patch is to fix
it by bringing it back.

Fixes: 248d45f1e193 ("openvswitch: Allow attaching helper in later commit")
Reported-by: Pablo Neira Ayuso <pablo@...filter.org>
Signed-off-by: Xin Long <lucien.xin@...il.com>
---
 net/openvswitch/conntrack.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
index 4e70df91d0f2..6862475f0f88 100644
--- a/net/openvswitch/conntrack.c
+++ b/net/openvswitch/conntrack.c
@@ -1015,7 +1015,8 @@ static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key,
 		 * connections which we will commit, we may need to attach
 		 * the helper here.
 		 */
-		if (info->commit && info->helper && !nfct_help(ct)) {
+		if (!nf_ct_is_confirmed(ct) && info->commit &&
+		    info->helper && !nfct_help(ct)) {
 			int err = __nf_ct_try_assign_helper(ct, info->ct,
 							    GFP_ATOMIC);
 			if (err)
-- 
2.31.1