netdev - [PATCH net] sctp: check duplicate node before inserting a new transport

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Date:   Fri, 17 Feb 2017 16:35:24 +0800
From:   Xin Long <lucien.xin@...il.com>
To:     network dev <netdev@...r.kernel.org>, linux-sctp@...r.kernel.org
Cc:     davem@...emloft.net,
        Marcelo Ricardo Leitner <marcelo.leitner@...il.com>,
        Neil Horman <nhorman@...driver.com>,
        Vlad Yasevich <vyasevich@...il.com>
Subject: [PATCH net] sctp: check duplicate node before inserting a new transport

sctp has changed to use rhlist for transport rhashtable since commit
7fda702f9315 ("sctp: use new rhlist interface on sctp transport
rhashtable").

But rhltable_insert_key doesn't check the duplicate node when inserting
a node, unlike rhashtable_lookup_insert_key. It may cause duplicate
assoc/transport in rhashtable. like:

 client (addr A, B)                 server (addr X, Y)
    connect to X           INIT (1)
                        ------------>
    connect to Y           INIT (2)
                        ------------>
                         INIT_ACK (1)
                        <------------
                         INIT_ACK (2)
                        <------------

After sending INIT (2), one transport will be created and hashed into
rhashtable. But when receiving INIT_ACK (1) and processing the address
params, another transport will be created and hashed into rhashtable
with the same addr Y and EP as the last transport. This will confuse
the assoc/transport's lookup.

This patch is to fix it by returning err if any duplicate node exists
before inserting it.

Fixes: 7fda702f9315 ("sctp: use new rhlist interface on sctp transport rhashtable")
Reported-by: Fabio M. Di Nitto <fdinitto@...hat.com>
Signed-off-by: Xin Long <lucien.xin@...il.com>
---
 net/sctp/input.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/net/sctp/input.c b/net/sctp/input.c
index 458e506..f65245b 100644
--- a/net/sctp/input.c
+++ b/net/sctp/input.c
@@ -872,6 +872,8 @@ void sctp_transport_hashtable_destroy(void)
 
 int sctp_hash_transport(struct sctp_transport *t)
 {
+	struct sctp_transport *transport;
+	struct rhlist_head *tmp, *list;
 	struct sctp_hash_cmp_arg arg;
 	int err;
 
@@ -882,8 +884,19 @@ int sctp_hash_transport(struct sctp_transport *t)
 	arg.paddr = &t->ipaddr;
 	arg.lport = htons(t->asoc->base.bind_addr.port);
 
+	list = rhltable_lookup(&sctp_transport_hashtable, &arg,
+			       sctp_hash_params);
+
+	rhl_for_each_entry_rcu(transport, tmp, list, node)
+		if (transport->asoc->ep == t->asoc->ep) {
+			err = -EEXIST;
+			goto out;
+		}
+
 	err = rhltable_insert_key(&sctp_transport_hashtable, &arg,
 				  &t->node, sctp_hash_params);
+
+out:
 	if (err)
 		pr_err_once("insert transport fail, errno %d\n", err);
 
-- 
2.1.0