CVE-2026-98870: falha de alta gravidade em Linux
ksmbd: remove stale channels from all sessions on teardown
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21Vexday Risk Score
Sem sinal de exploração. Nenhum artefato público de exploração conhecido até agora.
ssvc Trackcvss 8.8epss 0.5%
In the Linux kernel, the following vulnerability has been resolved:
ksmbd: remove stale channels from all sessions on teardown
ksmbd_sessions_deregister() removes a connection's channels from other
sessions' channel lists only while conn->binding is still set:
if (conn->binding) {
hash_for_each_safe(sessions_table, ...)
ksmbd_chann_del(conn, sess);
}
conn->binding is a transient flag: it is cleared once a binding
SESSION_SETUP completes, and also by a subsequent non-binding
SESSION_SETUP on the same connection (a reauthentication on a bound
channel, or a new SessionId==0 setup). A connection that has bound a
channel into another session's ksmbd_chann_list and then clears
conn->binding leaves that channel behind when it disconnects: the
channel, whose chann->conn points at the now freed struct ksmbd_conn,
stays on the owner session's list.
When the owning connection later tears down, the second loop
dereferences the stale channel:
xa_for_each(&sess->ksmbd_chann_list, chann_id, chann)
if (chann->conn != conn)
ksmbd_conn_set_exiting(chann->conn); /* freed */
which is a use-after-free write into the freed ksmbd_conn (the same
stale channel is also walked by show_proc_session() through /proc). The
session is leaked as well, because its channel list never empties.
Remove the conn->binding gate so a connection always removes its
channels from every session on teardown.
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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Referências
https://git.kernel.org/stable/c/9cd6d714d3ca0cff296542dc989696884e41970fhttps://git.kernel.org/stable/c/a15cae16f4432a5ad919ee633e31b07178492955https://git.kernel.org/stable/c/b10665730fbf6b5e45fe422badcbbc3f0df96ef5https://git.kernel.org/stable/c/b145f9b56c87f9c23ad5464ab0844dbc1de12b36https://git.kernel.org/stable/c/f8200bb4994e65a2e5c5b314789eeae39078619d