6.6-stable review patch. If anyone has any objections, please let me know.
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From: Paolo Abeni pabeni@redhat.com
commit 27fd02860164bfa78cec2640dfad630d832e302c upstream.
When __mptcp_retrans() kicks-in, it schedules one or more subflows for retransmission, but such subflows could be actually left alone if there is no more data to retransmit and/or in case of concurrent fallback.
Scheduled subflows could be processed much later in time, i.e. when new data will be transmitted, leading to bad subflow selection.
Explicitly clear all scheduled subflows before leaving the retransmission function.
Fixes: ee2708aedad0 ("mptcp: use get_retrans wrapper") Cc: stable@vger.kernel.org Reported-by: Filip Pokryvka fpokryvk@redhat.com Signed-off-by: Paolo Abeni pabeni@redhat.com Reviewed-by: Matthieu Baerts (NGI0) matttbe@kernel.org Signed-off-by: Matthieu Baerts (NGI0) matttbe@kernel.org Link: https://patch.msgid.link/20251125-net-mptcp-clear-sched-rtx-v1-1-1cea4ad2165... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org --- net/mptcp/protocol.c | 13 +++++++++++-- 1 file changed, 11 insertions(+), 2 deletions(-)
--- a/net/mptcp/protocol.c +++ b/net/mptcp/protocol.c @@ -2691,7 +2691,7 @@ static void __mptcp_retrans(struct sock }
if (!mptcp_send_head(sk)) - return; + goto clear_scheduled;
goto reset_timer; } @@ -2722,7 +2722,7 @@ static void __mptcp_retrans(struct sock if (__mptcp_check_fallback(msk)) { spin_unlock_bh(&msk->fallback_lock); release_sock(ssk); - return; + goto clear_scheduled; }
while (info.sent < info.limit) { @@ -2754,6 +2754,15 @@ reset_timer:
if (!mptcp_rtx_timer_pending(sk)) mptcp_reset_rtx_timer(sk); + +clear_scheduled: + /* If no rtx data was available or in case of fallback, there + * could be left-over scheduled subflows; clear them all + * or later xmit could use bad ones + */ + mptcp_for_each_subflow(msk, subflow) + if (READ_ONCE(subflow->scheduled)) + mptcp_subflow_set_scheduled(subflow, false); }
/* schedule the timeout timer for the relevant event: either close timeout