From: Wei Wang <weiwan@xxxxxxxxxx> This patch has been added to the v4.1 stable tree. If you have any objections, please let us know. =============== [ Upstream commit 499350a5a6e7512d9ed369ed63a4244b6536f4f8 ] 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@xxxxxxxxxx> Signed-off-by: Wei Wang <weiwan@xxxxxxxxxx> Signed-off-by: Eric Dumazet <edumazet@xxxxxxxxxx> Signed-off-by: Neal Cardwell <ncardwell@xxxxxxxxxx> Signed-off-by: Yuchung Cheng <ycheng@xxxxxxxxxx> Signed-off-by: David S. Miller <davem@xxxxxxxxxxxxx> Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxx> --- net/ipv4/tcp.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c index d935c9815564..1ba4d0964042 100644 --- a/net/ipv4/tcp.c +++ b/net/ipv4/tcp.c @@ -2220,6 +2220,10 @@ 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); -- 2.11.0