From 98247bc16a27cf8ead4c47ce9f15888be85841fc Mon Sep 17 00:00:00 2001 From: Paolo Abeni Date: Fri, 18 Feb 2022 13:35:40 -0800 Subject: [PATCH] mptcp: fix race in overlapping signal events After commit a88c9e496937 ("mptcp: do not block subflows creation on errors"), if a signal address races with a failing subflow creation, the subflow creation failure control path can trigger the selection of the next address to be announced while the current announced is still pending. The above will cause the unintended suppression of the ADD_ADDR announce. Fix the issue skipping the to-be-suppressed announce before it will mark an endpoint as already used. The relevant announce will be triggered again when the current one will complete. Fixes: a88c9e496937 ("mptcp: do not block subflows creation on errors") Reviewed-by: Matthieu Baerts Signed-off-by: Paolo Abeni Signed-off-by: Mat Martineau Signed-off-by: David S. Miller --- net/mptcp/pm_netlink.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/net/mptcp/pm_netlink.c b/net/mptcp/pm_netlink.c index 356f596..82f82a5 100644 --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -546,6 +546,16 @@ static void mptcp_pm_create_subflow_or_signal_addr(struct mptcp_sock *msk) if (msk->pm.add_addr_signaled < add_addr_signal_max) { local = select_signal_address(pernet, msk); + /* due to racing events on both ends we can reach here while + * previous add address is still running: if we invoke now + * mptcp_pm_announce_addr(), that will fail and the + * corresponding id will be marked as used. + * Instead let the PM machinery reschedule us when the + * current address announce will be completed. + */ + if (msk->pm.addr_signal & BIT(MPTCP_ADD_ADDR_SIGNAL)) + return; + if (local) { if (mptcp_pm_alloc_anno_list(msk, local)) { __clear_bit(local->addr.id, msk->pm.id_avail_bitmap); -- 2.7.4