Cory Snider fb0f15c89a daemon/libnetwork/osl: fix panic on repeated interface removal ...

Namespace.RemoveInterface closes the Interface's stopCh to stop the
unsolicited ARP/NA sender, but only unregisters the Interface from the
Namespace once the removal has completed. Several failure exits sit in
between, so a removal that fails part-way leaves the Interface
registered with a closed stopCh.

Callers tear interfaces down by iterating over Namespace.Interfaces, so
the same *Interface is handed back to RemoveInterface during a later
teardown, and the second close panics, taking down the API request
being served:

    http: panic serving @: close of closed channel

Seen in CI while disconnecting an endpoint during Sandbox.Refresh:
LinkSetNsFd failed with EBADF after the link had already been renamed
back to its source name, so the following re-join couldn't find the
link, and the rollback in Endpoint.sbJoin removed the same Interface
again.

Close stopCh through a sync.Once, so the ARP/NA sender is still
guaranteed to stop whether or not the netlink teardown succeeds, and
however many times removal is attempted. Keep leaving a failed
Interface registered in the Namespace: the link may still be present
there, and generateIfaceName relies on n.iFaces to avoid handing out
its name again.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Signed-off-by: Cory Snider <csnider@mirantis.com>

2026-07-29 15:03:39 -04:00

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