Bluetooth: SCO: fix sco_conn related locking and validity issues

Operations that check/update sk_state and access conn should hold
lock_sock, otherwise they can race.

The order of taking locks is hci_dev_lock > lock_sock > sco_conn_lock,
which is how it is in connect/disconnect_cfm -> sco_conn_del ->
sco_chan_del.

Fix locking in sco_connect to take lock_sock around updating sk_state
and conn.

sco_conn_del must not occur during sco_connect, as it frees the
sco_conn. Hold hdev->lock longer to prevent that.

sco_conn_add shall return sco_conn with valid hcon. Make it so also when
reusing an old SCO connection waiting for disconnect timeout (see
__sco_sock_close where conn->hcon is set to NULL).

This should not reintroduce the issue fixed in the earlier
commit 9a8ec9e8ebb5 ("Bluetooth: SCO: Fix possible circular locking
dependency on sco_connect_cfm"), the relevant fix of releasing lock_sock
in sco_sock_connect before acquiring hdev->lock is retained.

These changes mirror similar fixes earlier in ISO sockets.

Fixes: 9a8ec9e8ebb5 ("Bluetooth: SCO: Fix possible circular locking dependency on sco_connect_cfm")
Signed-off-by: Pauli Virtanen <pav@iki.fi>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c
index cd1a27a..7762604 100644 (file)
--- a/net/bluetooth/sco.c
+++ b/net/bluetooth/sco.c
@@ -126,8 +126,11 @@ static struct sco_conn *sco_conn_add(struct hci_conn *hcon)
        struct hci_dev *hdev = hcon->hdev;
        struct sco_conn *conn = hcon->sco_data;
 
-       if (conn)
+       if (conn) {
+               if (!conn->hcon)
+                       conn->hcon = hcon;
                return conn;
+       }
 
        conn = kzalloc(sizeof(struct sco_conn), GFP_KERNEL);
        if (!conn)
@@ -268,21 +271,21 @@ static int sco_connect(struct sock *sk)
                goto unlock;
        }
 
-       hci_dev_unlock(hdev);
-       hci_dev_put(hdev);
-
        conn = sco_conn_add(hcon);
        if (!conn) {
                hci_conn_drop(hcon);
-               return -ENOMEM;
+               err = -ENOMEM;
+               goto unlock;
        }
 
-       err = sco_chan_add(conn, sk, NULL);
-       if (err)
-               return err;
-
        lock_sock(sk);
 
+       err = sco_chan_add(conn, sk, NULL);
+       if (err) {
+               release_sock(sk);
+               goto unlock;
+       }
+
        /* Update source addr of the socket */
        bacpy(&sco_pi(sk)->src, &hcon->src);
 
@@ -296,8 +299,6 @@ static int sco_connect(struct sock *sk)
 
        release_sock(sk);
 
-       return err;
-
 unlock:
        hci_dev_unlock(hdev);
        hci_dev_put(hdev);