CVE-2026-64045

In the Linux kernel, the following vulnerability has been resolved:

ovpn: tcp - use cached peer pointer in ovpn_tcp_close()

ovpn_tcp_close() loads the ovpn_socket via rcu_dereference_sk_user_data()

under rcu_read_lock(), takes a reference on sock->peer, caches the peer

pointer in a local, and drops the read lock. It then passes sock->peer

(rather than the cached local) to ovpn_peer_del(), re-dereferencing the

ovpn_socket after the RCU read section has ended.

Unlike ovpn_tcp_sendmsg(), which uses the same "load under RCU, use

after unlock" pattern but is protected by lock_sock() held across the

function, ovpn_tcp_close() runs without the socket lock: inet_release()

invokes sk_prot->close() without taking lock_sock first.

ovpn_socket_release() can therefore complete its kref_put -> detach ->

synchronize_rcu -> kfree(sock) sequence concurrently, in the window

after ovpn_tcp_close() drops rcu_read_lock() but before it dereferences

sock->peer. The synchronize_rcu() in ovpn_socket_release() protects

readers that use the dereferenced pointer inside the RCU read section,

not those that escape the pointer to a local and use it afterwards.

A reproducer follows the pattern of commit 94560267d6c4 ("ovpn: tcp -

don't deref NULL sk_socket member after tcp_close()"): trigger a peer

removal (keepalive expiration or netlink OVPN_CMD_DEL_PEER) at the same

moment userspace closes the TCP fd. That commit fixed the detach-side

of the same race window; this one fixes the close-side at a different

victim.

Tighten the entry block to read sock->peer exactly once into the cached

peer local, and route all subsequent uses (the hold check, the

ovpn_peer_del() call, and the prot->close() invocation) through that

local. sock->peer is only ever written once in ovpn_socket_new() under

lock_sock(), before rcu_assign_sk_user_data() publishes the ovpn_socket,

and is never reassigned afterwards - but the previous multi-read pattern

made that invariant implicit rather than explicit. The same multi-read

shape exists in ovpn_tcp_recvmsg(), ovpn_tcp_sendmsg(),

ovpn_tcp_data_ready() and ovpn_tcp_write_space(); those will be cleaned

up via a dedicated helper in a follow-up net-next series.