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Bluetooth: SCO: hold sk properly in sco_conn_ready

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commit 4e37f6452d 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: 27c24fda62 ("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>
This commit is contained in:
Pauli Virtanen
2026-07-24 16:03:34 +02:00
committed by Greg Kroah-Hartman
parent 44a203afae
commit d141d9b769
1 changed files with 32 additions and 12 deletions
Download Patch File Download Diff File Expand all files Collapse all files
net/bluetooth/sco.c
+32 -12
View File
@@ -409,9 +409,13 @@ 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)
@@ -451,11 +455,13 @@ static void sco_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 (sco_pi(sk)->conn) {
sco_conn_lock(sco_pi(sk)->conn);
sco_pi(sk)->conn->sk = NULL;
sco_conn_unlock(sco_pi(sk)->conn);
}
release_sock(sk);
/* Kill poor orphan */
bt_sock_unlink(&sco_sk_list, sk);
@@ -1302,17 +1308,28 @@ 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) {
lock_sock(sk);
sco_sock_clear_timer(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 {
if (!conn->hcon)
return;
@@ -1327,13 +1344,15 @@ static void sco_conn_ready(struct sco_conn *conn)
sco_conn_lock(conn);
/* 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) {
sco_conn_unlock(conn);
release_sock(parent);
return;
}
if (!sk)
goto release;
sco_sock_init(sk, parent);
@@ -1351,9 +1370,10 @@ static void sco_conn_ready(struct sco_conn *conn)
/* Wake up parent */
parent->sk_data_ready(parent);
release:
sco_conn_unlock(conn);
release_sock(parent);
sock_put(parent);
}
}