[PATCH 5.16 0745/1017] net/sched: act_ct: fix ref leak when switching zones

Greg Kroah-Hartman
2022-04-05T10:08:03Z

From: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>

[ Upstream commit bcb74e132a76ce0502bb33d5b65533a4ed72d159 ]

When switching zones or network namespaces without doing a ct clear in
between, it is now leaking a reference to the old ct entry. That's
because tcf_ct_skb_nfct_cached() returns false and
tcf_ct_flow_table_lookup() may simply overwrite it.

The fix is to, as the ct entry is not reusable, free it already at
tcf_ct_skb_nfct_cached().

Reported-by: Florian Westphal <fw@strlen.de>
Fixes: 2f131de361f6 ("net/sched: act_ct: Fix flow table lookup after ct clear or switching zones")
Signed-off-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
net/sched/act_ct.c | 15 +++++++++------
1 file changed, 9 insertions(+), 6 deletions(-)

diff --git a/net/sched/act_ct.c b/net/sched/act_ct.c
index 240b3c5d2eb1..553bf41671a6 100644
--- a/net/sched/act_ct.c
+++ b/net/sched/act_ct.c
@@ -583,22 +583,25 @@ static bool tcf_ct_skb_nfct_cached(struct net *net, struct sk_buff *skb,
if (!ct)
return false;
if (!net_eq(net, read_pnet(&ct->ct_net)))
- return false;
+ goto drop_ct;
if (nf_ct_zone(ct)->id != zone_id)
- return false;
+ goto drop_ct;

/* Force conntrack entry direction. */
if (force && CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) {
if (nf_ct_is_confirmed(ct))
nf_ct_kill(ct);

- nf_ct_put(ct);
- nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
-
- return false;
+ goto drop_ct;
}

return true;
+
+drop_ct:
+ nf_ct_put(ct);
+ nf_ct_set(skb, NULL, IP_CT_UNTRACKED);
+
+ return false;
}

/* Trim the skb to the length specified by the IP/IPv6 header,
--
2.34.1