[SRU][F:linux-bluefield][PATCH] net/sched: act_ct: fix ref leak when switching zones

[Bodong Wang]

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

BugLink: https://launchpad.net/bugs/1979009

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 at 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 at gmail.com>
Signed-off-by: David S. Miller <davem at davemloft.net>
Signed-off-by: Paul Blakey <paulb at nvidia.com>
(backported from commit bcb74e132a76ce0502bb33d5b65533a4ed72d159)
[paul: use ct_put rather than conntrack_put]
Signed-off-by: Bodong Wang <bodong at nvidia.com>
---
 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 ed310be..0f44608 100644
--- a/net/sched/act_ct.c
+++ b/net/sched/act_ct.c
@@ -598,22 +598,25 @@ 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_conntrack_put(&ct->ct_general);
-		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,
-- 
1.8.3.1