CVE-2026-64523

In the Linux kernel, the following vulnerability has been resolved:<br /> <br /> net/handshake: Take a long-lived file reference at submit<br /> <br /> handshake_nl_accept_doit() needs the file pointer backing<br /> req-&gt;hr_sk-&gt;sk_socket to survive the window between<br /> handshake_req_next() and the subsequent FD_PREPARE() and get_file().<br /> The submit-side sock_hold() does not provide that. sk_refcnt keeps<br /> struct sock alive, but struct socket is owned by sock-&gt;file: when<br /> the consumer fputs the last file reference, sock_release() tears<br /> the socket down regardless of any sock_hold.<br /> <br /> Add an hr_file pointer to struct handshake_req and acquire an<br /> explicit reference on sock-&gt;file during handshake_req_submit().<br /> handshake_complete() and handshake_req_cancel() release the<br /> reference on the completion-bit-winning path.<br /> <br /> The submit error path must also release the file reference, but<br /> after rhashtable insertion a concurrent handshake_req_cancel() can<br /> discover the request and race the error path. Gate the error-path<br /> cleanup -- sk_destruct restoration, fput, and request destruction<br /> -- with test_and_set_bit(HANDSHAKE_F_REQ_COMPLETED), the same<br /> serialization handshake_complete() and handshake_req_cancel()<br /> already use. When cancel has already claimed ownership, the submit<br /> error path returns without touching the request; socket teardown<br /> handles final destruction.<br /> <br /> The accept-side dereferences are not yet retargeted; that change<br /> comes in the next patch.