From f745a3ebdfb9041d3a55e66eb345895cd8ecc90c Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Mon, 27 Jun 2022 18:02:39 -0700 Subject: [PATCH] mptcp: consistent map handling on failure When the MPTCP receive path reach a non fatal fall-back condition, e.g. when the MPC sockets must fall-back to TCP, the existing code is a little self-inconsistent: it reports that new data is available - return true - but sets the MPC flag to the opposite value. As the consequence read operations in some exceptional scenario may block unexpectedly. Address the issue setting the correct MPC read status. Additionally avoid some code duplication in the fatal fall-back scenario. Fixes: 9c81be0dbc89 ("mptcp: add MP_FAIL response support") Signed-off-by: Paolo Abeni Signed-off-by: Mat Martineau Signed-off-by: Jakub Kicinski --- net/mptcp/subflow.c | 19 +++++++++---------- 1 file changed, 9 insertions(+), 10 deletions(-) diff --git a/net/mptcp/subflow.c b/net/mptcp/subflow.c index b34b96fb742f..03862103665d 100644 --- a/net/mptcp/subflow.c +++ b/net/mptcp/subflow.c @@ -1252,17 +1252,12 @@ fallback: subflow->send_mp_fail = 1; if (!READ_ONCE(msk->allow_infinite_fallback)) { - ssk->sk_err = EBADMSG; - tcp_set_state(ssk, TCP_CLOSE); subflow->reset_transient = 0; subflow->reset_reason = MPTCP_RST_EMIDDLEBOX; - tcp_send_active_reset(ssk, GFP_ATOMIC); - while ((skb = skb_peek(&ssk->sk_receive_queue))) - sk_eat_skb(ssk, skb); - } else { - mptcp_subflow_fail(msk, ssk); + goto reset; } - WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_NODATA); + mptcp_subflow_fail(msk, ssk); + WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_DATA_AVAIL); return true; } @@ -1270,10 +1265,14 @@ fallback: /* fatal protocol error, close the socket. * subflow_error_report() will introduce the appropriate barriers */ - ssk->sk_err = EBADMSG; - tcp_set_state(ssk, TCP_CLOSE); subflow->reset_transient = 0; subflow->reset_reason = MPTCP_RST_EMPTCP; + +reset: + ssk->sk_err = EBADMSG; + tcp_set_state(ssk, TCP_CLOSE); + while ((skb = skb_peek(&ssk->sk_receive_queue))) + sk_eat_skb(ssk, skb); tcp_send_active_reset(ssk, GFP_ATOMIC); WRITE_ONCE(subflow->data_avail, MPTCP_SUBFLOW_NODATA); return false; -- 2.34.1