Hi Marcel,
No problem, thanks. Happy to extend userchan-tester; do you mind if we
continue reviewing this patch for approval in the meantime so we can
mitigate the issue on our end?
On Thu, Nov 11, 2021 at 12:43 PM Marcel Holtmann <marcel@xxxxxxxxxxxx> wrote:
>
> Hi Jesse,
>
> > A race condition is triggered when usermode control is given to
> > userspace before the kernel's MSFT query responds, resulting in an
> > unexpected response to userspace's reset command.
> >
> > Issue can be observed in btmon:
> > < HCI Command: Vendor (0x3f|0x001e) plen 2 #3 [hci0]
> > 05 01 ..
> > @ USER Open: bt_stack_manage (privileged) version 2.22 {0x0002} [hci0]
> > < HCI Command: Reset (0x03|0x0003) plen 0 #4 [hci0]
> >> HCI Event: Command Complete (0x0e) plen 5 #5 [hci0]
> > Vendor (0x3f|0x001e) ncmd 1
> > Status: Command Disallowed (0x0c)
> > 05 .
> >> HCI Event: Command Complete (0x0e) plen 4 #6 [hci0]
> > Reset (0x03|0x0003) ncmd 2
> > Status: Success (0x00)
> >
> > Signed-off-by: Jesse Melhuish <melhuishj@xxxxxxxxxxxx>
> > Reviewed-by: Abhishek Pandit-Subedi <abhishekpandit@xxxxxxxxxxxx>
> > Reviewed-by: Sonny Sasaka <sonnysasaka@xxxxxxxxxxxx>
> > ---
> >
> > Changes in v2:
> > - Moved guard to the new home for this code.
> >
> > net/bluetooth/hci_sync.c | 6 ++++--
> > 1 file changed, 4 insertions(+), 2 deletions(-)
> >
> > diff --git a/net/bluetooth/hci_sync.c b/net/bluetooth/hci_sync.c
> > index b794605dc882..5f1f59ac1813 100644
> > --- a/net/bluetooth/hci_sync.c
> > +++ b/net/bluetooth/hci_sync.c
> > @@ -3887,8 +3887,10 @@ int hci_dev_open_sync(struct hci_dev *hdev)
> > hci_dev_test_flag(hdev, HCI_VENDOR_DIAG) && hdev->set_diag)
> > ret = hdev->set_diag(hdev, true);
> >
> > - msft_do_open(hdev);
> > - aosp_do_open(hdev);
> > + if (!hci_dev_test_flag(hdev, HCI_USER_CHANNEL)) {
> > + msft_do_open(hdev);
> > + aosp_do_open(hdev);
> > + }
>
> but then you need to do the same on hci_dev_close. Also it would be good to extend userchan-tester with test cases for this.
>
> Regards
>
> Marcel
>
