From: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>

Date: Mon, 12 Sep 2022 01:21:42 +0900

Subject: Bluetooth: avoid hci_dev_test_and_set_flag() in mgmt_init_hdev()

Patch-mainline: v6.1-rc1

Git-commit: f74ca25d6d6629ffd4fd80a1a73037253b57d06b

References: jsc#PED-1407

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 <penguin-kernel@I-love.SAKURA.ne.jp>

Fixes: 3f2893d3c142986a ("Bluetooth: don't try to cancel uninitialized works at mgmt_index_removed()")

Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>

Acked-by: Lee, Chun-Yi <jlee@suse.com>

---

 net/bluetooth/mgmt.c |    4 +++-

 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/net/bluetooth/mgmt.c

+++ b/net/bluetooth/mgmt.c

@@ -1050,7 +1050,7 @@ static void discov_off(struct work_struc

 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 *

 	 * 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,