netdev - [PATCH net-next] net: sched: do not allocate a tracker in tcf_exts

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Date:   Mon, 10 Jan 2022 01:47:50 -0800
From:   Eric Dumazet <eric.dumazet@...il.com>
To:     "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev <netdev@...r.kernel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        Eric Dumazet <eric.dumazet@...il.com>,
        syzbot <syzkaller@...glegroups.com>
Subject: [PATCH net-next] net: sched: do not allocate a tracker in tcf_exts_init()

From: Eric Dumazet <edumazet@...gle.com>

While struct tcf_exts has a net pointer, it is not refcounted
until tcf_exts_get_net() is called.

Fixes: dbdcda634ce3 ("net: sched: add netns refcount tracker to struct tcf_exts")
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Reported-by: syzbot <syzkaller@...glegroups.com>
---
 include/net/pkt_cls.h | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/include/net/pkt_cls.h b/include/net/pkt_cls.h
index ebef45e821afd51e407dc19d83d0ad10759e7aba..676cb8ea9e15cae4b098b461918ea0ff49d97768 100644
--- a/include/net/pkt_cls.h
+++ b/include/net/pkt_cls.h
@@ -218,8 +218,10 @@ static inline int tcf_exts_init(struct tcf_exts *exts, struct net *net,
 #ifdef CONFIG_NET_CLS_ACT
 	exts->type = 0;
 	exts->nr_actions = 0;
+	/* Note: we do not own yet a reference on net.
+	 * This reference might be taken later from tcf_exts_get_net().
+	 */
 	exts->net = net;
-	netns_tracker_alloc(net, &exts->ns_tracker, GFP_KERNEL);
 	exts->actions = kcalloc(TCA_ACT_MAX_PRIO, sizeof(struct tc_action *),
 				GFP_KERNEL);
 	if (!exts->actions)
-- 
2.34.1.575.g55b058a8bb-goog