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,