tcp: fix listening_get_next()

Alexey Vlasov found /proc/net/tcp could sometime loop and display
millions of sockets in LISTEN state.

In 2.6.29, when we converted TCP hash tables to RCU, we left two
sk_next() calls in listening_get_next().

We must instead use sk_nulls_next() to properly detect an end of chain.

Reported-by: Alexey Vlasov <renton@renton.name>
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index e13da6de1fc79e26dc6d03b671e1becf9e6c8754..d978bb2f748b34d99efb0162e4e083a460275630 100644 (file)
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2030,7 +2030,7 @@ static void *listening_get_next(struct seq_file *seq, void *cur)
 get_req:
                        req = icsk->icsk_accept_queue.listen_opt->syn_table[st->sbucket];
                }
-               sk        = sk_next(st->syn_wait_sk);
+               sk        = sk_nulls_next(st->syn_wait_sk);
                st->state = TCP_SEQ_STATE_LISTENING;
                read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
        } else {
@@ -2039,7 +2039,7 @@ get_req:
                if (reqsk_queue_len(&icsk->icsk_accept_queue))
                        goto start_req;
                read_unlock_bh(&icsk->icsk_accept_queue.syn_wait_lock);
-               sk = sk_next(sk);
+               sk = sk_nulls_next(sk);
        }
 get_sk:
        sk_nulls_for_each_from(sk, node) {