[PATCH 2/2] Bluetooth: SCO: fix sco_conn related locking and validity issues

Alexander Ofitserov
2024-02-26T13:28:59Z

From: Pauli Virtanen <pav@iki.fi>

commit 3dcaa192ac21 ("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>
Signed-off-by: Alexander Ofitserov <oficerovas@altlinux.org>
Cc: stable@vger.kernel.org
---
net/bluetooth/sco.c | 23 ++++++++++++-----------
1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/net/bluetooth/sco.c b/net/bluetooth/sco.c
index 0e1f5dde7bfec..99b149261949a 100644
--- 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);
--
2.42.1