Commit 470f7a68 authored Jul 28, 2021 by Desmond Cheong Zhi Xi Committed by Greg Kroah-Hartman Sep 22, 2021

Bluetooth: skip invalid hci_sync_conn_complete_evt

[ Upstream commit 92fe24a7db751b80925214ede43f8d2be792ea7b ]

Syzbot reported a corrupted list in kobject_add_internal [1]. This
happens when multiple HCI_EV_SYNC_CONN_COMPLETE event packets with
status 0 are sent for the same HCI connection. This causes us to
register the device more than once which corrupts the kset list.

As this is forbidden behavior, we add a check for whether we're
trying to process the same HCI_EV_SYNC_CONN_COMPLETE event multiple
times for one connection. If that's the case, the event is invalid, so
we report an error that the device is misbehaving, and ignore the
packet.

Link: https://syzkaller.appspot.com/bug?extid=66264bf2fd0476be7e6c

 [1]
Reported-by:  <syzbot+66264bf2fd0476be7e6c@syzkaller.appspotmail.com>
Tested-by:  <syzbot+66264bf2fd0476be7e6c@syzkaller.appspotmail.com>
Signed-off-by: Desmond Cheong Zhi Xi <desmondcheongzx@gmail.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent 614bf36b

net/bluetooth/hci_event.c

+15 −0

Original line number	Diff line number	Diff line
		@@ -3747,6 +3747,21 @@ static void hci_sync_conn_complete_evt(struct hci_dev *hdev,

		switch (ev->status) {
		case 0x00:
		/* The synchronous connection complete event should only be
		* sent once per new connection. Receiving a successful
		* complete event when the connection status is already
		* BT_CONNECTED means that the device is misbehaving and sent
		* multiple complete event packets for the same new connection.
		*
		* Registering the device more than once can corrupt kernel
		* memory, hence upon detecting this invalid event, we report
		* an error and ignore the packet.
		*/
		if (conn->state == BT_CONNECTED) {
		bt_dev_err(hdev, "Ignoring connect complete event for existing connection");
		goto unlock;
		}

		conn->handle = __le16_to_cpu(ev->handle);
		conn->state = BT_CONNECTED;
		conn->type = ev->link_type;