FAILED: patch "[PATCH] net/sched: act_ct: remove 'add_helper' dead code" failed to apply to 6.6-stable tree

FAILED: patch "[PATCH] net/sched: act_ct: remove 'add_helper' dead code" failed to apply to 6.6-stable tree

[gregkh]

The patch below does not apply to the 6.6-stable tree.
If someone wants it applied there, or to any other stable or longterm
tree, then please email the backport, including the original git commit
id to <stable@vger.kernel.org>.

To reproduce the conflict and resubmit, you may use the following commands:

git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y
git checkout FETCH_HEAD
git cherry-pick -x 00df72e39f306e2f7adb68528a5c92109da6a0a9
# <resolve conflicts, build, test, etc.>
git commit -s
git send-email --to '<stable@vger.kernel.org>' --in-reply-to '2026092940-dropout-pebbly-3736@gregkh' --subject-prefix 'PATCH 6.6.y' 'HEAD^..'

Possible dependencies:



thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From 00df72e39f306e2f7adb68528a5c92109da6a0a9 Mon Sep 17 00:00:00 2001
From: Ilya Maximets <i.maximets@ovn.org>
Date: Mon, 21 Sep 2026 16:55:47 +0200
Subject: [PATCH] net/sched: act_ct: remove 'add_helper' dead code

This variable can only become 'true' when the connection is not
confirmed, but it is only checked when it is confirmed.  So, it can be
treated as being always false and just removed.

Fixes: a21b06e73191 ("net: sched: add helper support in act_ct")
Cc: stable@vger.kernel.org
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
Reviewed-by: Aaron Conole <aconole@redhat.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20260921145655.3167436-6-i.maximets@ovn.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c
index e72143d36b11..f62051ec9d57 100644
--- a/net/sched/act_ct.c
+++ b/net/sched/act_ct.c
@@ -986,7 +986,6 @@ TC_INDIRECT_SCOPE int tcf_ct_act(struct sk_buff *skb, const struct tc_action *a,
 	struct nf_hook_state state;
 	int nh_ofs, err, retval;
 	struct tcf_ct_params *p;
-	bool add_helper = false;
 	bool skb_is_ours = false;
 	bool skip_add = false;
 	bool defrag = false;
@@ -1096,14 +1095,14 @@ TC_INDIRECT_SCOPE int tcf_ct_act(struct sk_buff *skb, const struct tc_action *a,
 		err = __nf_ct_try_assign_helper(ct, p->tmpl, GFP_ATOMIC);
 		if (err)
 			goto drop;
-		add_helper = true;
+
 		if (nat && !nfct_seqadj(ct)) {
 			if (!nfct_seqadj_ext_add(ct))
 				goto drop;
 		}
 	}
 
-	if (nf_ct_is_confirmed(ct) ? ((!cached && !skip_add) || add_helper) : commit) {
+	if (nf_ct_is_confirmed(ct) ? (!cached && !skip_add) : commit) {
 		err = nf_ct_helper(skb, ct, ctinfo, family);
 		if (err != NF_ACCEPT)
 			goto nf_error;

[PATCH 6.6.y 1/2] net: openvswitch: conntrack: avoid modifying shared unconfirmed ct entry

[Sasha Levin]

From: Ilya Maximets <i.maximets@ovn.org>

[ Upstream commit 26b2bd70d22457556e2fa01cbf1192cb1a94d619 ]

In a case where skb with an unconfirmed ct entry gets cloned, we may
end up committing both but with different sets of extensions.

The series of events:

 1. The first clone wants to commit and runs the helpers wiring up
    the extension pointer into the expectation list.
 2. Then it looses the confirmation keeping the entry unconfirmed.
 3. Second clone now wants to commit labels and adds the new extension
    for that breaking the pointer in the expectation list causing
    UAF on the destruction path later.

While this is possible to trigger, there should be no practical
network pipeline where committing both clones without modifications
into the same zone is needed.  So, let's just reset the entry in case
for some reason we got an skb with a shared one during commit.  This
doesn't affect any known use cases, but avoids any potential problems
with sharing and modification of the unconfirmed ct entry.

The fixes tag points to the introduction of helpers, since that's the
main UAF trigger for the sharing.

Fixes: cae3a2627520 ("openvswitch: Allow attaching helpers to ct action")
Cc: stable@vger.kernel.org
Reported-by: Axel Mierczuk <axel.mierczuk@1password.com>
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
Reviewed-by: Aaron Conole <aconole@redhat.com>
Link: https://patch.msgid.link/20260921145655.3167436-2-i.maximets@ovn.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Stable-dep-of: 00df72e39f30 ("net/sched: act_ct: remove 'add_helper' dead code")
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 include/net/netfilter/nf_conntrack.h |  5 +++++
 net/openvswitch/conntrack.c          | 12 ++++++++++++
 2 files changed, 17 insertions(+)

diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h
index a2c987289401e..3b41312cb0b02 100644
--- a/include/net/netfilter/nf_conntrack.h
+++ b/include/net/netfilter/nf_conntrack.h
@@ -190,6 +190,11 @@ static inline void nf_ct_put(struct nf_conn *ct)
 		nf_ct_destroy(&ct->ct_general);
 }
 
+static inline bool nf_ct_shared(const struct nf_conn *ct)
+{
+	return refcount_read(&ct->ct_general.use) > 1;
+}
+
 /* load module; enable/disable conntrack in this namespace */
 int nf_ct_netns_get(struct net *net, u8 nfproto);
 void nf_ct_netns_put(struct net *net, u8 nfproto);
diff --git a/net/openvswitch/conntrack.c b/net/openvswitch/conntrack.c
index 6ceec146e694f..ac8d19779d287 100644
--- a/net/openvswitch/conntrack.c
+++ b/net/openvswitch/conntrack.c
@@ -716,6 +716,18 @@ static int __ovs_ct_lookup(struct net *net, struct sw_flow_key *key,
 	enum ip_conntrack_info ctinfo;
 	struct nf_conn *ct;
 
+	/* If the ct entry is not confirmed and shared with some other skb,
+	 * e.g., a cloned one, we can't just modify it with the commit as we
+	 * must not modify the extension set.  Reset.
+	 */
+	if (cached && info->commit) {
+		ct = nf_ct_get(skb, &ctinfo);
+		if (ct && !nf_ct_is_confirmed(ct) && nf_ct_shared(ct)) {
+			nf_reset_ct(skb);
+			cached = false;
+		}
+	}
+
 	if (!cached) {
 		struct nf_hook_state state = {
 			.hook = NF_INET_PRE_ROUTING,
-- 
2.53.0

[PATCH 6.6.y 2/2] net/sched: act_ct: remove 'add_helper' dead code

[Sasha Levin]

From: Ilya Maximets <i.maximets@ovn.org>

[ Upstream commit 00df72e39f306e2f7adb68528a5c92109da6a0a9 ]

This variable can only become 'true' when the connection is not
confirmed, but it is only checked when it is confirmed.  So, it can be
treated as being always false and just removed.

Fixes: a21b06e73191 ("net: sched: add helper support in act_ct")
Cc: stable@vger.kernel.org
Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
Reviewed-by: Aaron Conole <aconole@redhat.com>
Reviewed-by: Xin Long <lucien.xin@gmail.com>
Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
Link: https://patch.msgid.link/20260921145655.3167436-6-i.maximets@ovn.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
[ adjusted context to preserve the direct NAT flag check and goto drop error handling. ]
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 net/sched/act_ct.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c
index 7a0dff24c5d15..bdffceeb4f34d 100644
--- a/net/sched/act_ct.c
+++ b/net/sched/act_ct.c
@@ -981,7 +981,6 @@ TC_INDIRECT_SCOPE int tcf_ct_act(struct sk_buff *skb, const struct tc_action *a,
 	bool cached, commit, clear;
 	int nh_ofs, err, retval;
 	struct tcf_ct_params *p;
-	bool add_helper = false;
 	bool skb_is_ours = false;
 	bool skip_add = false;
 	bool defrag = false;
@@ -1077,14 +1076,14 @@ TC_INDIRECT_SCOPE int tcf_ct_act(struct sk_buff *skb, const struct tc_action *a,
 		err = __nf_ct_try_assign_helper(ct, p->tmpl, GFP_ATOMIC);
 		if (err)
 			goto drop;
-		add_helper = true;
+
 		if (p->ct_action & TCA_CT_ACT_NAT && !nfct_seqadj(ct)) {
 			if (!nfct_seqadj_ext_add(ct))
 				goto drop;
 		}
 	}
 
-	if (nf_ct_is_confirmed(ct) ? ((!cached && !skip_add) || add_helper) : commit) {
+	if (nf_ct_is_confirmed(ct) ? (!cached && !skip_add) : commit) {
 		if (nf_ct_helper(skb, ct, ctinfo, family) != NF_ACCEPT)
 			goto drop;
 	}
-- 
2.53.0