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Date:   Thu,  6 Oct 2022 15:45:02 -0400
From:   Xin Long <>
To:     network dev <>,
        Eric Dumazet <>,
        Paolo Abeni <>,
        Pravin B Shelar <>,
        Florian Westphal <>,
        Pablo Neira Ayuso <>,
        Ilya Maximets <>,
        Eelco Chaudron <>,
        Yi-Hung Wei <>
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:
   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]

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 <>
Signed-off-by: Xin Long <>
 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,
 			if (err)

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