CVE-2026-45918

Summary

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

ovpn: tcp - don't deref NULL sk_socket member after tcp_close()

When deleting a peer in case of keepalive expiration, the peer is removed from the OpenVPN hashtable and is temporary inserted in a "release list" for further processing.

This happens in: ovpn_peer_keepalive_work() unlock_ovpn(release_list)

This processing includes detaching from the socket being used to talk to this peer, by restoring its original proto and socket ops/callbacks.

In case of TCP it may happen that, while the peer is sitting in the release list, userspace decides to close the socket. This will result in a concurrent execution of:

tcp_close(sk) __tcp_close(sk) sock_orphan(sk) sk_set_socket(sk, NULL)

The last function call will set sk->sk_socket to NULL.

When the releasing routine is resumed, ovpn_tcp_socket_detach() will attempt to dereference sk->sk_socket to restore its original ops member. This operation will crash due to sk->sk_socket being NULL.

Fix this race condition by testing-and-accessing sk->sk_socket atomically under sk->sk_callback_lock.

Affected Software

Weaknesses

References

• https://git.kernel.org/stable/c/f998b2c4bec487063a586695159f9a1856e81c56
• https://git.kernel.org/stable/c/b9142cf4e066c825ec68752a7dcaceda700bbe26
• https://git.kernel.org/stable/c/94560267d6c41b1ff3fafbab726e3f8a55a6af34

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