tcp: memset ca_priv data to 0 properly

Always zero out ca_priv data in tcp_assign_congestion_control() so that
ca_priv data is cleared out during socket creation.
Also always zero out ca_priv data in tcp_reinit_congestion_control() so
that when cc algorithm is changed, ca_priv data is cleared out as well.
We should still zero out ca_priv data even in TCP_CLOSE state because
user could call connect() on AF_UNSPEC to disconnect the socket and
leave it in TCP_CLOSE state and later call setsockopt() to switch cc
algorithm on this socket.

Fixes: 2b0a8c9ee ("tcp: add CDG congestion control")
Reported-by: Andrey Konovalov  <andreyknvl@google.com>
Signed-off-by: Wei Wang <weiwan@google.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Acked-by: Yuchung Cheng <ycheng@google.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 8 deletions

diff --git a/net/ipv4/tcp_cong.c b/net/ipv4/tcp_cong.c
index 79c4817abc94..6e3c512054a6 100644
--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -168,12 +168,8 @@ void tcp_assign_congestion_control(struct sock *sk)
         }
 out:
         rcu_read_unlock();
+        memset(icsk->icsk_ca_priv, 0, sizeof(icsk->icsk_ca_priv));
 
-        /* Clear out private data before diag gets it and
-         * the ca has not been initialized.
-         */
-        if (ca->get_info)
-                memset(icsk->icsk_ca_priv, 0, sizeof(icsk->icsk_ca_priv));
         if (ca->flags & TCP_CONG_NEEDS_ECN)
                 INET_ECN_xmit(sk);
         else
@@ -200,11 +196,10 @@ static void tcp_reinit_congestion_control(struct sock *sk,
         tcp_cleanup_congestion_control(sk);
         icsk->icsk_ca_ops = ca;
         icsk->icsk_ca_setsockopt = 1;
+        memset(icsk->icsk_ca_priv, 0, sizeof(icsk->icsk_ca_priv));
 
-        if (sk->sk_state != TCP_CLOSE) {
-                memset(icsk->icsk_ca_priv, 0, sizeof(icsk->icsk_ca_priv));
+        if (sk->sk_state != TCP_CLOSE)
                 tcp_init_congestion_control(sk);
-        }
 }
 
 /* Manage refcounts on socket close. */