From: Desmond Cheong Zhi Xi desmondcheongzx@gmail.com
stable inclusion from linux-4.19.207 commit a2f1874e084dba7ab08da5b7ce363ad6b871c64d
--------------------------------
[ 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 Signed-off-by: Yang Yingliang yangyingliang@huawei.com --- net/bluetooth/hci_event.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+)
diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c index 45cc864cf2b38..714a45355610a 100644 --- a/net/bluetooth/hci_event.c +++ b/net/bluetooth/hci_event.c @@ -4083,6 +4083,21 @@ 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;