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Commit 499350a5 authored by Wei Wang's avatar Wei Wang Committed by David S. Miller
Browse files

tcp: initialize rcv_mss to TCP_MIN_MSS instead of 0 



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: default avatarAndrey Konovalov <andreyknvl@google.com>
Signed-off-by: default avatarWei Wang <weiwan@google.com>
Signed-off-by: default avatarEric Dumazet <edumazet@google.com>
Signed-off-by: default avatarNeal Cardwell <ncardwell@google.com>
Signed-off-by: default avatarYuchung Cheng <ycheng@google.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 23416e23

net/ipv4/tcp.c

+4 −0
Original line number Diff line number Diff line
@@ -2320,6 +2320,10 @@ int tcp_disconnect(struct sock *sk, int flags) 
	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);