Commit dad19b59da05 for kernel

commit dad19b59da050cb60d3f7023dac2a042a84bf0bd
Author: Ilya Maximets <i.maximets@ovn.org>
Date:   Mon Sep 21 16:55:48 2026 +0200

    net/sched: act_ct: fix helper UAF due to extensions realloc

    While calling the helpers, a raw pointer to the extensions area is
    wired into expectations list:

      -> nf_ct_helper()
       -> helper->help()
        -> nf_ct_expect_related_report()
         -> nf_ct_expect_insert()
          -> hlist_add_head_rcu(&exp->lnode, &master_help->expectations)

    In case the connection is not confirmed yet, more extensions can be
    added afterwards with *_ext_add() calls reallocating the extension
    space and leaving the now invalid pointer in the expectations list
    that is later accessed while removing the expectation.

    Make sure that helpers are called at the end after all the other
    extensions are already added.

    Note that the helper rejection now leaves the mark and labels set,
    but that's not different from how the NAT was handled before or how
    the mark and the labels were handled on confirmation failure.  And
    there are no atomicity guarantees provided by the API anyway.

    Fixes: a21b06e73191 ("net: sched: add helper support in act_ct")
    Cc: stable@vger.kernel.org
    Reported-by: Axel Mierczuk <axel.mierczuk@1password.com>
    Signed-off-by: Ilya Maximets <i.maximets@ovn.org>
    Reviewed-by: Xin Long <lucien.xin@gmail.com>
    Reviewed-by: Jamal Hadi Salim <jhs@mojatatu.com>
    Reviewed-by: Aaron Conole <aconole@redhat.com>
    Link: https://patch.msgid.link/20260921145655.3167436-7-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 f62051ec9d57..411e3dd92d07 100644
--- a/net/sched/act_ct.c
+++ b/net/sched/act_ct.c
@@ -1102,19 +1102,25 @@ TC_INDIRECT_SCOPE int tcf_ct_act(struct sk_buff *skb, const struct tc_action *a,
 		}
 	}

-	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;
-	}
-
 	if (commit) {
 		tcf_ct_act_set_mark(ct, p->mark, p->mark_mask);
 		tcf_ct_act_set_labels(ct, p->labels, p->labels_mask);

 		if (!nf_ct_is_confirmed(ct))
 			nf_conn_act_ct_ext_add(skb, ct, ctinfo);
+	}

+	/* Run helpers for the connection if nf_conntrack_in() was executed
+	 * or if we're about to commit.  This has to be done after all the
+	 * extensions are already added.
+	 */
+	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;
+	}
+
+	if (commit) {
 		/* This will take care of sending queued events
 		 * even if the connection is already confirmed.
 		 */