From: Pauli Virtanen <pav@iki.fi> stable inclusion from stable-v5.15.212 commit 50aae396dc30377bec8e3b181b8346f8fd38f7d8 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/19595 CVE: CVE-2026-89774 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- commit 4e37f6452d586b95c346a9abdd2fb80b67794f39 upstream. sk deref in sco_conn_ready must be done either under conn->lock, or holding a refcount, to avoid concurrent close. conn->sk and parent sk is currently accessed without either, and without checking parent->sk_state: [Task 1] [Task 2] sco_sock_release sco_conn_ready sk = conn->sk lock_sock(sk) conn->sk = NULL lock_sock(sk) release_sock(sk) sco_sock_kill(sk) UAF on sk deref and similarly for access to sco_get_sock_listen() return value. Fix possible UAF by holding sk refcount in sco_conn_ready() and making sco_get_sock_listen() increase refcount. Also recheck after lock_sock that the socket is still valid. Adjust conn->sk locking so it's protected also by lock_sock() of the associated socket if any. Fixes: 27c24fda62b60 ("Bluetooth: switch to lock_sock in SCO") Signed-off-by: Pauli Virtanen <pav@iki.fi> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Conflicts: net/bluetooth/sco.c [ Context conflicts ] Signed-off-by: Yao Yiqi <yaoyiqi3@huawei.com> --- net/bluetooth/sco.c | 42 ++++++++++++++++++++++++++++++------------ 1 file changed, 30 insertions(+), 12 deletions(-) diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c index 5dbd7e6e1481..33480cc5e853 100644 --- a/net/bluetooth/sco.c +++ b/net/bluetooth/sco.c @@ -372,9 +372,13 @@ static struct sock *sco_get_sock_listen(bdaddr_t *src) sk1 = sk; } + sk = sk ? sk : sk1; + if (sk) + sock_hold(sk); + read_unlock(&sco_sk_list.lock); - return sk ? sk : sk1; + return sk; } static void sco_sock_destruct(struct sock *sk) @@ -1108,17 +1112,28 @@ static int sco_sock_release(struct socket *sock) static void sco_conn_ready(struct sco_conn *conn) { - struct sock *parent; - struct sock *sk = conn->sk; + struct sock *parent, *sk; + + sco_conn_lock(conn); + sk = sco_sock_hold(conn); + sco_conn_unlock(conn); BT_DBG("conn %p", conn); if (sk) { - sco_sock_clear_timer(sk); lock_sock(sk); - sk->sk_state = BT_CONNECTED; - sk->sk_state_change(sk); + + /* conn->sk may have become NULL if racing with sk close, but + * due to held hdev->lock, it can't become different sk. + */ + if (conn->sk) { + sco_sock_clear_timer(sk); + sk->sk_state = BT_CONNECTED; + sk->sk_state_change(sk); + } + release_sock(sk); + sock_put(sk); } else { sco_conn_lock(conn); @@ -1135,13 +1150,15 @@ static void sco_conn_ready(struct sco_conn *conn) lock_sock(parent); + /* hdev->lock guarantees conn->sk == NULL still here */ + + if (parent->sk_state != BT_LISTEN) + goto release; + sk = sco_sock_alloc(sock_net(parent), NULL, BTPROTO_SCO, GFP_ATOMIC, 0); - if (!sk) { - release_sock(parent); - sco_conn_unlock(conn); - return; - } + if (!sk) + goto release; sco_sock_init(sk, parent); @@ -1159,9 +1176,10 @@ static void sco_conn_ready(struct sco_conn *conn) /* Wake up parent */ parent->sk_data_ready(parent); +release: release_sock(parent); - sco_conn_unlock(conn); + sock_put(parent); } } -- 2.34.1