11.04.2024 18:19, kovalev@altlinux.org wrote:

From: Vasiliy Kovalev kovalev@altlinux.org

When returning from the hci_disconnect() function, the conn->state continues to be set to BT_CONNECTED and hci_conn_drop() is executed, which decrements the conn->refcnt.

Syzkaller C reproducer: https://lore.kernel.org/all/f8bb62a7-5845-53ed-7fbe-c0557c2745f2@basealt.ru/...

During debugging, the value conn->refcnt goes down to -1000 and less.

Syzkaller has generated a reproducer that results in multiple calls to hci_encrypt_change_evt() of the same conn object. -- hci_encrypt_change_evt(){ // conn->state == BT_CONNECTED hci_disconnect(){ hci_abort_conn(); } hci_conn_drop(); // conn->state == BT_CONNECTED } -- This behavior can cause the conn->refcnt to go far into negative values and cause problems. To get around this, you need to change the conn->state, namely to BT_DISCONN, as it was before. > Fixes: a13f316e90fd ("Bluetooth: hci_conn: Consolidate code for

aborting connections")

Cc: stable@vger.kernel.org Signed-off-by: Vasiliy Kovalev kovalev@altlinux.org

---

net/bluetooth/hci_event.c | 3 +++ 1 file changed, 3 insertions(+)

diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c index 64477e1bde7cec..e0477021183f9b 100644 --- a/net/bluetooth/hci_event.c +++ b/net/bluetooth/hci_event.c @@ -2989,6 +2989,7 @@ static void hci_cs_le_start_enc(struct hci_dev *hdev, u8 status) hci_disconnect(conn, HCI_ERROR_AUTH_FAILURE); hci_conn_drop(conn);

• conn->state = BT_DISCONN;

unlock: hci_dev_unlock(hdev); @@ -3654,6 +3655,7 @@ static void hci_encrypt_change_evt(struct hci_dev *hdev, void *data, hci_encrypt_cfm(conn, ev->status); hci_disconnect(conn, HCI_ERROR_AUTH_FAILURE); hci_conn_drop(conn);

• conn->state = BT_DISCONN;
  

  goto unlock; }

@@ -5248,6 +5250,7 @@ static void hci_key_refresh_complete_evt(struct hci_dev *hdev, void *data, if (ev->status && conn->state == BT_CONNECTED) { hci_disconnect(conn, HCI_ERROR_AUTH_FAILURE); hci_conn_drop(conn);

• conn->state = BT_DISCONN;
  

  goto unlock; }