syzbot is again reporting attempt to cancel uninitialized work at mgmt_index_removed() [1], for setting of HCI_MGMT flag from mgmt_init_hdev() from hci_mgmt_cmd() from hci_sock_sendmsg() can race with testing of HCI_MGMT flag from mgmt_index_removed() from hci_sock_bind() due to lack of serialization via hci_dev_lock(). Since mgmt_init_hdev() is called with mgmt_chan_list_lock held, we can safely split hci_dev_test_and_set_flag() into hci_dev_test_flag() and hci_dev_set_flag(). Thus, in order to close this race, set HCI_MGMT flag after INIT_DELAYED_WORK() completed. This is a local fix based on mgmt_chan_list_lock. Lack of serialization via hci_dev_lock() might be causing different race conditions somewhere else. But a global fix based on hci_dev_lock() should deserve a future patch. Link: https://syzkaller.appspot.com/bug?extid=844c7bf1b1aa4119c5de Reported-by: syzbot+844c7bf1b1aa4119c5de@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> Fixes: 3f2893d3c142986a ("Bluetooth: don't try to cancel uninitialized works at mgmt_index_removed()") --- net/bluetooth/mgmt.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/net/bluetooth/mgmt.c b/net/bluetooth/mgmt.c index 72e6595a71cc..3d1cd0666968 100644 --- a/net/bluetooth/mgmt.c +++ b/net/bluetooth/mgmt.c @@ -1050,7 +1050,7 @@ static void discov_off(struct work_struct *work) static void mgmt_init_hdev(struct sock *sk, struct hci_dev *hdev) { - if (hci_dev_test_and_set_flag(hdev, HCI_MGMT)) + if (hci_dev_test_flag(hdev, HCI_MGMT)) return; BT_INFO("MGMT ver %d.%d", MGMT_VERSION, MGMT_REVISION); @@ -1065,6 +1065,8 @@ static void mgmt_init_hdev(struct sock *sk, struct hci_dev *hdev) * it */ hci_dev_clear_flag(hdev, HCI_BONDABLE); + + hci_dev_set_flag(hdev, HCI_MGMT); } static int read_controller_info(struct sock *sk, struct hci_dev *hdev, -- 2.18.4
