Re: [PATCH for 4.4] bluetooth: eliminate the potential race condition when removing the HCI controller

[Greg KH <gregkh@linuxfoundation.org>]

On Fri, May 28, 2021 at 05:52:24PM +0900, Nobuhiro Iwamatsu wrote:
> From: Lin Ma <linma@zju.edu.cn>
> 
> commit e2cb6b891ad2b8caa9131e3be70f45243df82a80 upstream.
> 
> 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>
> [iwamatsu: adjust filename, arguments of __hci_req_sync(). CVE-2021-32399]
> Signed-off-by: Nobuhiro Iwamatsu <nobuhiro1.iwamatsu@toshiba.co.jp>
> ---
>  net/bluetooth/hci_core.c | 13 +++++++++----
>  1 file changed, 9 insertions(+), 4 deletions(-)

Now queued up, thanks.

greg k-h