tcp/dccp: fix inet_reuseport_add_sock()

David Ahern reported panics in __inet_hash() caused by my recent commit.

The reason is inet_reuseport_add_sock() was still using
sk_nulls_for_each_rcu() instead of sk_for_each_rcu().
SO_REUSEPORT enabled listeners were causing an instant crash.

While chasing this bug, I found that I forgot to clear SOCK_RCU_FREE
flag, as it is inherited from the parent at clone time.

Fixes: 3b24d854cb35 ("tcp/dccp: do not touch listener sk_refcnt under synflood")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Reported-by: David Ahern <dsa@cumulusnetworks.com>
Tested-by: David Ahern <dsa@cumulusnetworks.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 4 insertions, 2 deletions

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index bc5196ea1bdf..ab69da2d2a77 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -661,6 +661,9 @@ struct sock *inet_csk_clone_lock(const struct sock *sk,
                 inet_sk(newsk)->inet_sport = htons(inet_rsk(req)->ir_num);
                 newsk->sk_write_space = sk_stream_write_space;
 
+                /* listeners have SOCK_RCU_FREE, not the children */
+                sock_reset_flag(newsk, SOCK_RCU_FREE);
+
                 newsk->sk_mark = inet_rsk(req)->ir_mark;
                 atomic64_set(&newsk->sk_cookie,
                              atomic64_read(&inet_rsk(req)->ir_cookie));
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index 98ba03b6f87d..fcadb670f50b 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -439,10 +439,9 @@ static int inet_reuseport_add_sock(struct sock *sk,
                                                      bool match_wildcard))
 {
         struct sock *sk2;
-        struct hlist_nulls_node *node;
         kuid_t uid = sock_i_uid(sk);
 
-        sk_nulls_for_each_rcu(sk2, node, &ilb->head) {
+        sk_for_each_rcu(sk2, &ilb->head) {
                 if (sk2 != sk &&
                     sk2->sk_family == sk->sk_family &&
                     ipv6_only_sock(sk2) == ipv6_only_sock(sk) &&