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Date: Sat, 09 Sep 2017 22:47:40 +0100
From: Ben Hutchings <ben@...adent.org.uk>
To: linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC: akpm@...ux-foundation.org,
"Andrey Konovalov" <andreyknvl@...gle.com>,
"Eric Dumazet" <edumazet@...gle.com>,
"Neal Cardwell" <ncardwell@...gle.com>,
"David S. Miller" <davem@...emloft.net>,
"Yuchung Cheng" <ycheng@...gle.com>, "Wei Wang" <weiwan@...gle.com>
Subject: [PATCH 3.2 098/106] tcp: initialize rcv_mss to TCP_MIN_MSS
instead of 0
3.2.93-rc1 review patch. If anyone has any objections, please let me know.
------------------
From: Wei Wang <weiwan@...gle.com>
commit 499350a5a6e7512d9ed369ed63a4244b6536f4f8 upstream.
When tcp_disconnect() is called, inet_csk_delack_init() sets
icsk->icsk_ack.rcv_mss to 0.
This could potentially cause tcp_recvmsg() => tcp_cleanup_rbuf() =>
__tcp_select_window() call path to have division by 0 issue.
So this patch initializes rcv_mss to TCP_MIN_MSS instead of 0.
Reported-by: Andrey Konovalov <andreyknvl@...gle.com>
Signed-off-by: Wei Wang <weiwan@...gle.com>
Signed-off-by: Eric Dumazet <edumazet@...gle.com>
Signed-off-by: Neal Cardwell <ncardwell@...gle.com>
Signed-off-by: Yuchung Cheng <ycheng@...gle.com>
Signed-off-by: David S. Miller <davem@...emloft.net>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
net/ipv4/tcp.c | 4 ++++
1 file changed, 4 insertions(+)
--- a/net/ipv4/tcp.c
+++ b/net/ipv4/tcp.c
@@ -2106,6 +2106,10 @@ int tcp_disconnect(struct sock *sk, int
tcp_set_ca_state(sk, TCP_CA_Open);
tcp_clear_retrans(tp);
inet_csk_delack_init(sk);
+ /* Initialize rcv_mss to TCP_MIN_MSS to avoid division by 0
+ * issue in __tcp_select_window()
+ */
+ icsk->icsk_ack.rcv_mss = TCP_MIN_MSS;
tcp_init_send_head(sk);
memset(&tp->rx_opt, 0, sizeof(tp->rx_opt));
__sk_dst_reset(sk);
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