Hi Greg,
On 26/08/2024 14:06, gregkh@linuxfoundation.org wrote:
The patch below does not apply to the 5.15-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to stable@vger.kernel.org.
Thank you for the notification!
(...)
------------------ original commit in Linus's tree ------------------
From 322ea3778965da72862cca2a0c50253aacf65fe6 Mon Sep 17 00:00:00 2001 From: "Matthieu Baerts (NGI0)" matttbe@kernel.org Date: Mon, 19 Aug 2024 21:45:26 +0200 Subject: [PATCH] mptcp: pm: only mark 'subflow' endp as available
Adding the following warning ...
WARN_ON_ONCE(msk->pm.local_addr_used == 0)
... before decrementing the local_addr_used counter helped to find a bug when running the "remove single address" subtest from the mptcp_join.sh selftests.
Removing a 'signal' endpoint will trigger the removal of all subflows linked to this endpoint via mptcp_pm_nl_rm_addr_or_subflow() with rm_type == MPTCP_MIB_RMSUBFLOW. This will decrement the local_addr_used counter, which is wrong in this case because this counter is linked to 'subflow' endpoints, and here it is a 'signal' endpoint that is being removed.
Now, the counter is decremented, only if the ID is being used outside of mptcp_pm_nl_rm_addr_or_subflow(), only for 'subflow' endpoints, and if the ID is not 0 -- local_addr_used is not taking into account these ones. This marking of the ID as being available, and the decrement is done no matter if a subflow using this ID is currently available, because the subflow could have been closed before.
Fixes: 06faa2271034 ("mptcp: remove multi addresses and subflows in PM")
Similar to my previous message linked to the backport of "mptcp: pm: re-using ID of unused removed ADD_ADDR" where this patch depends on 86e39e04482b ("mptcp: keep track of local endpoint still available for each msk"), I don't think we need to backport this patch to v5.15.
Cheers, Matt