On Fri, Feb 17, 2017 at 04:35:24PM +0800, Xin Long wrote:
> 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@xxxxxxxxxx>
> Signed-off-by: Xin Long <lucien.xin@xxxxxxxxx>
> ---
> 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;
> + }
> +
Maybe its just a little early, but I'm rather lost as to how this works. When
you insert a key to the rhltable, its a sctp_hash_cmp_arg that gets inserted,
which is a struct that consists of a sctp_addr union, a struct net, and a u16,
but when you traverse the list for lookup, you treat the returned list as a list
of sctp_transport structs that you compare. That seems very wrong.
Neil
> 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
>
>
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