From f74ca25d6d6629ffd4fd80a1a73037253b57d06b Mon Sep 17 00:00:00 2001 From: Tetsuo Handa Date: Mon, 12 Sep 2022 01:21:42 +0900 Subject: [PATCH] Bluetooth: avoid hci_dev_test_and_set_flag() in mgmt_init_hdev() 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@syzkaller.appspotmail.com Signed-off-by: Tetsuo Handa Fixes: 3f2893d3c142986a ("Bluetooth: don't try to cancel uninitialized works at mgmt_index_removed()") Signed-off-by: Luiz Augusto von Dentz --- 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 4c421eb..b9b6403 100644 --- a/net/bluetooth/mgmt.c +++ b/net/bluetooth/mgmt.c @@ -1111,7 +1111,7 @@ static void mesh_send_done(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); @@ -1127,6 +1127,8 @@ 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, -- 2.7.4