In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
ovpn: tcp – use cached peer pointer in ovpn_tcp_close()<\/p>\n
ovpn_tcp_close() loads the ovpn_socket via rcu_dereference_sk_user_data()
\nunder rcu_read_lock(), takes a reference on sock->peer, caches the peer
\npointer in a local, and drops the read lock. It then passes sock->peer
\n(rather than the cached local) to ovpn_peer_del(), re-dereferencing the
\novpn_socket after the RCU read section has ended.<\/p>\n
Unlike ovpn_tcp_sendmsg(), which uses the same “load under RCU, use
\nafter unlock” pattern but is protected by lock_sock() held across the
\nfunction, ovpn_tcp_close() runs without the socket lock: inet_release()
\ninvokes sk_prot->close() without taking lock_sock first.<\/p>\n
ovpn_socket_release() can therefore complete its kref_put -> detach ->
\nsynchronize_rcu -> kfree(sock) sequence concurrently, in the window
\nafter ovpn_tcp_close() drops rcu_read_lock() but before it dereferences
\nsock->peer. The synchronize_rcu() in ovpn_socket_release() protects
\nreaders that use the dereferenced pointer inside the RCU read section,
\nnot those that escape the pointer to a local and use it afterwards.<\/p>\n
A reproducer follows the pattern of commit 94560267d6c4 (“ovpn: tcp –
\ndon’t deref NULL sk_socket member after tcp_close()”): trigger a peer
\nremoval (keepalive expiration or netlink OVPN_CMD_DEL_PEER) at the same
\nmoment userspace closes the TCP fd. That commit fixed the detach-side
\nof the same race window; this one fixes the close-side at a different
\nvictim.<\/p>\n
Tighten the entry block to read sock->peer exactly once into the cached
\npeer local, and route all subsequent uses (the hold check, the
\novpn_peer_del() call, and the prot->close() invocation) through that
\nlocal. sock->peer is only ever written once in ovpn_socket_new() under
\nlock_sock(), before rcu_assign_sk_user_data() publishes the ovpn_socket,
\nand is never reassigned afterwards – but the previous multi-read pattern
\nmade that invariant implicit rather than explicit. The same multi-read
\nshape exists in ovpn_tcp_recvmsg(), ovpn_tcp_sendmsg(),
\novpn_tcp_data_ready() and ovpn_tcp_write_space(); those will be cleaned
\nup via a dedicated helper in a follow-up net-next series.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the Linux kernel, the following vulnerability has been resolved:<\/p>\n
ovpn: tcp – use cached peer pointer in ovpn_tcp_close()<\/p>\n
ovpn_tcp_close() loads the ovpn_socket via rcu_dereference_sk_user_data()<\/p>\n","protected":false},"template":"","meta":[],"categories":[],"tags":[],"class_list":["post-15034","vuln","type-vuln","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln\/15034","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/vuln"}],"about":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=\/wp\/v2\/types\/vuln"}],"wp:attachment":[{"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=15034"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=15034"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.54iter.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=15034"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}