sctp: proc: protect bind_addr->address_list accesses with rcu_read_lock()

address_list is protected via the socket lock or RCU. Since we don't want
to take the socket lock for each assoc we dump in procfs a RCU read-side
critical section must be entered.

V2: Skip local addresses marked as dead

Cc: Vlad Yasevich <vyasevich@gmail.com>
Cc: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: NThomas Graf <tgraf@suug.ch>
Acked-by: NVlad Yasevich <vyasevic@gmail.com>
Acked-by: NNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sctp/proc.c

@@ -139,7 +139,11 @@ static void sctp_seq_dump_local_addrs(struct seq_file *seq, struct sctp_ep_commo
 	    primary = &peer->saddr;
 	}
 
-	list_for_each_entry(laddr, &epb->bind_addr.address_list, list) {
+	rcu_read_lock();
+	list_for_each_entry_rcu(laddr, &epb->bind_addr.address_list, list) {
+		if (!laddr->valid)
+			continue;
+
 		addr = &laddr->a;
 		af = sctp_get_af_specific(addr->sa.sa_family);
 		if (primary && af->cmp_addr(addr, primary)) {
@@ -147,6 +151,7 @@ static void sctp_seq_dump_local_addrs(struct seq_file *seq, struct sctp_ep_commo
 		}
 		af->seq_dump_addr(seq, addr);
 	}
+	rcu_read_unlock();
 }
 
 /* Dump remote addresses of an association. */