6.6-stable review patch. If anyone has any objections, please let me know. ------------------ From: Pauli Virtanen [ Upstream commit 0d255e63fcf3f13a570d7ac11678fa1164ac015c ] sk deref in iso_conn_ready must be done either under conn->lock, or holding a refcount, to avoid concurrent close. conn->sk is currently accessed without either: [Task 1] [Task 2] iso_sock_release iso_conn_ready sk = conn->sk lock_sock(sk) conn->sk = NULL lock_sock(sk) release_sock(sk) iso_sock_kill(sk) UAF on sk deref Fix possible UAF by holding sk refcount in iso_conn_ready(). Also recheck after lock_sock that the socket is still valid. Adjust locking so conn->sk is cleared only under lock_sock. Fixes: 27c24fda62b60 ("Bluetooth: switch to lock_sock in SCO") Signed-off-by: Pauli Virtanen Signed-off-by: Luiz Augusto von Dentz Signed-off-by: Sasha Levin --- net/bluetooth/iso.c | 29 +++++++++++++++++++++++------ 1 file changed, 23 insertions(+), 6 deletions(-) diff --git a/net/bluetooth/iso.c b/net/bluetooth/iso.c index 2dd8e6e6beac5..0bce3f1759dd2 100644 --- a/net/bluetooth/iso.c +++ b/net/bluetooth/iso.c @@ -735,11 +735,13 @@ static void iso_sock_kill(struct sock *sk) BT_DBG("sk %p state %d", sk, sk->sk_state); /* Sock is dead, so set conn->sk to NULL to avoid possible UAF */ + lock_sock(sk); if (iso_pi(sk)->conn) { iso_conn_lock(iso_pi(sk)->conn); iso_pi(sk)->conn->sk = NULL; iso_conn_unlock(iso_pi(sk)->conn); } + release_sock(sk); /* Kill poor orphan */ bt_sock_unlink(&iso_sk_list, sk); @@ -1696,14 +1698,11 @@ static void iso_sock_ready(struct sock *sk) { BT_DBG("sk %p", sk); - if (!sk) - return; + lockdep_assert(lockdep_sock_is_held(sk)); - lock_sock(sk); iso_sock_clear_timer(sk); sk->sk_state = BT_CONNECTED; sk->sk_state_change(sk); - release_sock(sk); } struct iso_list_data { @@ -1726,7 +1725,7 @@ static bool iso_match_pa_sync_flag(struct sock *sk, void *data) static void iso_conn_ready(struct iso_conn *conn) { struct sock *parent = NULL; - struct sock *sk = conn->sk; + struct sock *sk; struct hci_ev_le_big_sync_estabilished *ev = NULL; struct hci_ev_le_pa_sync_established *ev2 = NULL; struct hci_evt_le_big_info_adv_report *ev3 = NULL; @@ -1734,8 +1733,26 @@ static void iso_conn_ready(struct iso_conn *conn) BT_DBG("conn %p", conn); + iso_conn_lock(conn); + sk = iso_sock_hold(conn); + iso_conn_unlock(conn); + if (sk) { - iso_sock_ready(conn->sk); + lock_sock(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) { + release_sock(sk); + sock_put(sk); + return; + } + + iso_sock_ready(sk); + + release_sock(sk); + sock_put(sk); } else { hcon = conn->hcon; if (!hcon) -- 2.53.0