| From | Ben Hutchings <> | Date | Sat, 09 Sep 2017 22:47:40 +0100 | Subject | [PATCH 3.2 098/106] tcp: initialize rcv_mss to TCP_MIN_MSS instead of 0 |
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3.2.93-rc1 review patch. If anyone has any objections, please let me know.
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From: Wei Wang <weiwan@google.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@google.com> Signed-off-by: Wei Wang <weiwan@google.com> Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Ben Hutchings <ben@decadent.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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