From: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx> commit 9366922adc6a71378ca01f898c41be295309f044 upstream. 'local_addr_used' and 'add_addr_accepted' are decremented for addresses not related to the initial subflow (ID0), because the source and destination addresses of the initial subflows are known from the beginning: they don't count as "additional local address being used" or "ADD_ADDR being accepted". It is then required not to increment them when the entrypoint used by the initial subflow is removed and re-added during a connection. Without this modification, this entrypoint cannot be removed and re-added more than once. Reported-by: Arınç ÜNAL <arinc.unal@xxxxxxxxxx> Closes: https://github.com/multipath-tcp/mptcp_net-next/issues/512 Fixes: 3ad14f54bd74 ("mptcp: more accurate MPC endpoint tracking") Reported-by: syzbot+455d38ecd5f655fc45cf@xxxxxxxxxxxxxxxxxxxxxxxxx Closes: https://lore.kernel.org/00000000000049861306209237f4@xxxxxxxxxx Cc: stable@xxxxxxxxxxxxxxx Tested-by: Arınç ÜNAL <arinc.unal@xxxxxxxxxx> Reviewed-by: Mat Martineau <martineau@xxxxxxxxxx> Signed-off-by: Matthieu Baerts (NGI0) <matttbe@xxxxxxxxxx> Signed-off-by: Paolo Abeni <pabeni@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- net/mptcp/pm_netlink.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) --- a/net/mptcp/pm_netlink.c +++ b/net/mptcp/pm_netlink.c @@ -615,12 +615,13 @@ subflow: fullmesh = !!(local.flags & MPTCP_PM_ADDR_FLAG_FULLMESH); - msk->pm.local_addr_used++; __clear_bit(local.addr.id, msk->pm.id_avail_bitmap); /* Special case for ID0: set the correct ID */ if (local.addr.id == msk->mpc_endpoint_id) local.addr.id = 0; + else /* local_addr_used is not decr for ID 0 */ + msk->pm.local_addr_used++; nr = fill_remote_addresses_vec(msk, &local.addr, fullmesh, addrs); if (nr == 0) @@ -750,7 +751,9 @@ static void mptcp_pm_nl_add_addr_receive spin_lock_bh(&msk->pm.lock); if (sf_created) { - msk->pm.add_addr_accepted++; + /* add_addr_accepted is not decr for ID 0 */ + if (remote.id) + msk->pm.add_addr_accepted++; if (msk->pm.add_addr_accepted >= add_addr_accept_max || msk->pm.subflows >= subflows_max) WRITE_ONCE(msk->pm.accept_addr, false); Patches currently in stable-queue which might be from matttbe@xxxxxxxxxx are queue-6.10/selftests-mptcp-join-cannot-rm-sf-if-closed.patch queue-6.10/mptcp-pm-fix-rm_addr-id-for-the-initial-subflow.patch queue-6.10/mptcp-pm-fix-id-0-endp-usage-after-multiple-re-creations.patch queue-6.10/mptcp-pm-skip-connecting-to-already-established-sf.patch queue-6.10/mptcp-pm-reuse-id-0-after-delete-and-re-add.patch queue-6.10/mptcp-avoid-duplicated-sub_closed-events.patch queue-6.10/mptcp-pm-add_addr-0-is-not-a-new-address.patch queue-6.10/mptcp-pm-do-not-remove-already-closed-subflows.patch queue-6.10/mptcp-pm-send-ack-on-an-active-subflow.patch queue-6.10/mptcp-pm-reset-mpc-endp-id-when-re-added.patch queue-6.10/mptcp-close-subflow-when-receiving-tcp-fin.patch queue-6.10/selftests-mptcp-join-check-re-re-adding-id-0-endp.patch queue-6.10/selftests-mptcp-join-no-extra-msg-if-no-counter.patch queue-6.10/mptcp-pr_debug-add-missing-n-at-the-end.patch queue-6.10/selftests-mptcp-join-check-removing-id-0-endpoint.patch queue-6.10/mptcp-sched-check-both-backup-in-retrans.patch
