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| author |   Lin Ma <linma@zju.edu.cn> | 2021-04-12 19:17:57 +0800 |
|---|---|---|
| committer |   Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2021-04-23 13:25:04 +0200 |
| commit | e2cb6b891ad2b8caa9131e3be70f45243df82a80 (patch) | |
| tree | d90080640acfe6a6b6885e96b171154b77cbabf5 | |
| parent | coresight: etm-perf: Fix define build issue when built as module (diff) | |
| download | linux-dev-e2cb6b891ad2b8caa9131e3be70f45243df82a80.tar.xz linux-dev-e2cb6b891ad2b8caa9131e3be70f45243df82a80.zip | |
bluetooth: eliminate the potential race condition when removing the HCI controller
There is a possible race condition vulnerability between issuing a HCI
command and removing the cont. Specifically, functions hci_req_sync()
and hci_dev_do_close() can race each other like below:
thread-A in hci_req_sync() | thread-B in hci_dev_do_close()
| hci_req_sync_lock(hdev);
test_bit(HCI_UP, &hdev->flags); |
... | test_and_clear_bit(HCI_UP, &hdev->flags)
hci_req_sync_lock(hdev); |
|
In this commit we alter the sequence in function hci_req_sync(). Hence,
the thread-A cannot issue th.
Signed-off-by: Lin Ma <linma@zju.edu.cn>
Cc: Marcel Holtmann <marcel@holtmann.org>
Fixes: 7c6a329e4447 ("[Bluetooth] Fix regression from using default link policy")
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | net/bluetooth/hci_request.c | 12 |
1 files changed, 8 insertions, 4 deletions
diff --git a/net/bluetooth/hci_request.c b/net/bluetooth/hci_request.c index e55976db4403..805ce546b813 100644 --- a/net/bluetooth/hci_request.c +++ b/net/bluetooth/hci_request.c @@ -272,12 +272,16 @@ int hci_req_sync(struct hci_dev *hdev, int (*req)(struct hci_request *req, { int ret; - if (!test_bit(HCI_UP, &hdev->flags)) - return -ENETDOWN; - /* Serialize all requests */ hci_req_sync_lock(hdev); - ret = __hci_req_sync(hdev, req, opt, timeout, hci_status); + /* check the state after obtaing the lock to protect the HCI_UP + * against any races from hci_dev_do_close when the controller + * gets removed. + */ + if (test_bit(HCI_UP, &hdev->flags)) + ret = __hci_req_sync(hdev, req, opt, timeout, hci_status); + else + ret = -ENETDOWN; hci_req_sync_unlock(hdev); return ret; |