On Fri, May 28, 2021 at 05:52:24PM +0900, Nobuhiro Iwamatsu wrote:

From: Lin Ma <redacted>

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 <redacted>
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 <redacted>
---
 net/bluetooth/hci_core.c | 13 +++++++++----
 1 file changed, 9 insertions(+), 4 deletions(-)

Now queued up, thanks.

greg k-h