| From foo@baz Thu Sep 14 23:20:08 PDT 2017 |
| From: Wei Wang <weiwan@google.com> |
| Date: Thu, 18 May 2017 11:22:33 -0700 |
| Subject: tcp: initialize rcv_mss to TCP_MIN_MSS instead of 0 |
| |
| From: Wei Wang <weiwan@google.com> |
| |
| |
| [ 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@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: Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
| --- |
| net/ipv4/tcp.c | 4 ++++ |
| 1 file changed, 4 insertions(+) |
| |
| --- a/net/ipv4/tcp.c |
| +++ b/net/ipv4/tcp.c |
| @@ -2297,6 +2297,10 @@ 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); |