From: Cen Zhang <zzzccc427@gmail.com> stable inclusion from stable-v6.6.134 commit adb90cd0f9f7a8d438fcb93354040fbafc5ae2a0 category: bugfix bugzilla: https://atomgit.com/src-openeuler/kernel/issues/14555 CVE: CVE-2026-43023 Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=... -------------------------------- [ Upstream commit 8a5b0135d4a5d9683203a3d9a12a711ccec5936b ] sco_sock_connect() checks sk_state and sk_type without holding the socket lock. Two concurrent connect() syscalls on the same socket can both pass the check and enter sco_connect(), leading to use-after-free. The buggy scenario involves three participants and was confirmed with additional logging instrumentation: Thread A (connect): HCI disconnect: Thread B (connect): sco_sock_connect(sk) sco_sock_connect(sk) sk_state==BT_OPEN sk_state==BT_OPEN (pass, no lock) (pass, no lock) sco_connect(sk): sco_connect(sk): hci_dev_lock hci_dev_lock hci_connect_sco <- blocked -> hcon1 sco_conn_add->conn1 lock_sock(sk) sco_chan_add: conn1->sk = sk sk->conn = conn1 sk_state=BT_CONNECT release_sock hci_dev_unlock hci_dev_lock sco_conn_del: lock_sock(sk) sco_chan_del: sk->conn=NULL conn1->sk=NULL sk_state= BT_CLOSED SOCK_ZAPPED release_sock hci_dev_unlock (unblocked) hci_connect_sco -> hcon2 sco_conn_add -> conn2 lock_sock(sk) sco_chan_add: sk->conn=conn2 sk_state= BT_CONNECT // zombie sk! release_sock hci_dev_unlock Thread B revives a BT_CLOSED + SOCK_ZAPPED socket back to BT_CONNECT. Subsequent cleanup triggers double sock_put() and use-after-free. Meanwhile conn1 is leaked as it was orphaned when sco_conn_del() cleared the association. Fix this by: - Moving lock_sock() before the sk_state/sk_type checks in sco_sock_connect() to serialize concurrent connect attempts - Fixing the sk_type != SOCK_SEQPACKET check to actually return the error instead of just assigning it - Adding a state re-check in sco_connect() after lock_sock() to catch state changes during the window between the locks - Adding sco_pi(sk)->conn check in sco_chan_add() to prevent double-attach of a socket to multiple connections - Adding hci_conn_drop() on sco_chan_add failure to prevent HCI connection leaks Fixes: 9a8ec9e8ebb5 ("Bluetooth: SCO: Fix possible circular locking dependency on sco_connect_cfm") Signed-off-by: Cen Zhang <zzzccc427@gmail.com> Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com> Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Liu Kai <liukai284@huawei.com> --- net/bluetooth/sco.c | 26 +++++++++++++++++++++----- 1 file changed, 21 insertions(+), 5 deletions(-) diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c index 56d8a2a26a7a..0ec5686489a1 100644 --- a/net/bluetooth/sco.c +++ b/net/bluetooth/sco.c @@ -298,7 +298,7 @@ static int sco_chan_add(struct sco_conn *conn, struct sock *sk, int err = 0; sco_conn_lock(conn); - if (conn->sk) + if (conn->sk || sco_pi(sk)->conn) err = -EBUSY; else __sco_chan_add(conn, sk, parent); @@ -352,9 +352,20 @@ static int sco_connect(struct sock *sk) lock_sock(sk); + /* Recheck state after reacquiring the socket lock, as another + * thread may have changed it (e.g., closed the socket). + */ + if (sk->sk_state != BT_OPEN && sk->sk_state != BT_BOUND) { + release_sock(sk); + hci_conn_drop(hcon); + err = -EBADFD; + goto unlock; + } + err = sco_chan_add(conn, sk, NULL); if (err) { release_sock(sk); + hci_conn_drop(hcon); goto unlock; } @@ -652,13 +663,18 @@ static int sco_sock_connect(struct socket *sock, struct sockaddr *addr, int alen addr->sa_family != AF_BLUETOOTH) return -EINVAL; - if (sk->sk_state != BT_OPEN && sk->sk_state != BT_BOUND) + lock_sock(sk); + + if (sk->sk_state != BT_OPEN && sk->sk_state != BT_BOUND) { + release_sock(sk); return -EBADFD; + } - if (sk->sk_type != SOCK_SEQPACKET) - err = -EINVAL; + if (sk->sk_type != SOCK_SEQPACKET) { + release_sock(sk); + return -EINVAL; + } - lock_sock(sk); /* Set destination address and psm */ bacpy(&sco_pi(sk)->dst, &sa->sco_bdaddr); release_sock(sk); -- 2.34.1