linux-kernel - [PATCH 4.10 42/62] tcp: memset ca

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Date:   Mon,  1 May 2017 14:34:55 -0700
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org, Andrey Konovalov <andreyknvl@...gle.com>,
        Wei Wang <weiwan@...gle.com>,
        Eric Dumazet <edumazet@...gle.com>,
        Yuchung Cheng <ycheng@...gle.com>,
        Neal Cardwell <ncardwell@...gle.com>,
        "David S. Miller" <davem@...emloft.net>
Subject: [PATCH 4.10 42/62] tcp: memset ca_priv data to 0 properly

4.10-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Wei Wang <weiwan@...gle.com>


[ Upstream commit c1201444075009507a6818de6518e2822b9a87c8 ]

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@...gle.com>
Signed-off-by: Wei Wang <weiwan@...gle.com>
Acked-by: Eric Dumazet <edumazet@...gle.com>
Acked-by: Yuchung Cheng <ycheng@...gle.com>
Acked-by: Neal Cardwell <ncardwell@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/ipv4/tcp_cong.c |   11 +++--------
 1 file changed, 3 insertions(+), 8 deletions(-)

--- a/net/ipv4/tcp_cong.c
+++ b/net/ipv4/tcp_cong.c
@@ -168,12 +168,8 @@ void tcp_assign_congestion_control(struc
 	}
 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_contro
 	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. */