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Bluetooth: skip invalid hci_sync_conn_complete_evt

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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>
This commit is contained in:
Desmond Cheong Zhi Xi 2021-07-28 15:51:04 +08:00 committed by Marcel Holtmann
parent a25fca4d3c
commit 92fe24a7db
1 changed files with 15 additions and 0 deletions
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15
net/bluetooth/hci_event.c
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@ -4382,6 +4382,21 @@ static void hci_sync_conn_complete_evt(struct hci_dev *hdev,
switch (ev->status) { switch (ev->status) {
case 0x00: 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->handle = __le16_to_cpu(ev->handle);
conn->state = BT_CONNECTED; conn->state = BT_CONNECTED;
conn->type = ev->link_type; conn->type = ev->link_type;