Merge tag 'ovpn-net-20250603' of https://github.com/OpenVPN/ovpn-net-next

Antonio Quartulli says:

====================
In this batch you can find the following bug fixes:

Patch 1: when releasing a UDP socket we were wrongly invoking
setup_udp_tunnel_sock() with an empty config. This was not
properly shutting down the UDP encap state.
With this patch we simply undo what was done during setup.

Patch 2: ovpn was holding a reference to a 'struct socket'
without increasing its reference counter. This was intended
and worked as expected until we hit a race condition where
user space tries to close the socket while kernel space is
also releasing it. In this case the (struct socket *)->sk
member would disappear under our feet leading to a null-ptr-deref.
This patch fixes this issue by having struct ovpn_socket hold
a reference directly to the sk member while also increasing
its reference counter.

Patch 3: in case of errors along the TCP RX path (softirq)
we want to immediately delete the peer, but this operation may
sleep. With this patch we move the peer deletion to a scheduled
worker.

Patch 4 and 5 are instead fixing minor issues in the ovpn
kselftests.

* tag 'ovpn-net-20250603' of https://github.com/OpenVPN/ovpn-net-next:
  selftest/net/ovpn: fix missing file
  selftest/net/ovpn: fix TCP socket creation
  ovpn: avoid sleep in atomic context in TCP RX error path
  ovpn: ensure sk is still valid during cleanup
  ovpn: properly deconfigure UDP-tunnel
====================

Link: https://patch.msgid.link/20250603111110.4575-1-antonio@openvpn.net/
Signed-off-by: Paolo Abeni <pabeni@redhat.com>