Re: [PATCH] bluetooth: fix uninitialized variables notify_evt

[Jackie Liu <liu.yun@xxxxxxxxx>]

Hi, Marcel.

在 2021/11/16 上午1:27, Marcel Holtmann 写道:
> Hi Jackie,
>
> > Coverity Scan report:
> >
> > [...]
> > *** CID 1493985:  Uninitialized variables  (UNINIT)
> > /net/bluetooth/hci_event.c: 4535 in hci_sync_conn_complete_evt()
> > 4529
> > 4530     	/* Notify only in case of SCO over HCI transport data path which
> > 4531     	 * is zero and non-zero value shall be non-HCI transport data path
> > 4532     	 */
> > 4533     	if (conn->codec.data_path == 0) {
> > 4534     		if (hdev->notify)
> > > > >     CID 1493985:  Uninitialized variables  (UNINIT)
> > > > >     Using uninitialized value "notify_evt" when calling "*hdev->notify".
> > 4535     			hdev->notify(hdev, notify_evt);
> > 4536     	}
> > 4537
> > 4538     	hci_connect_cfm(conn, ev->status);
> > 4539     	if (ev->status)
> > 4540     		hci_conn_del(conn);
> > [...]
> >
> > Although only btusb uses air_mode, and he only handles HCI_NOTIFY_ENABLE_SCO_CVSD
> > and HCI_NOTIFY_ENABLE_SCO_TRANSP, there is still a very small chance that
> > ev->air_mode is not equal to 0x2 and 0x3, but notify_evt is initialized to
> > HCI_NOTIFY_ENABLE_SCO_CVSD or HCI_NOTIFY_ENABLE_SCO_TRANSP. the context is
> > maybe not correct.
> >
> > In order to ensure 100% correctness, we directly give him a default value 0.
> >
> > Addresses-Coverity: ("Uninitialized variables")
> > Fixes: f4f9fa0c07bb ("Bluetooth: Allow usb to auto-suspend when SCO use	non-HCI transport")
> > Signed-off-by: Jackie Liu <liuyun01@xxxxxxxxxx>
> > ---
> > net/bluetooth/hci_event.c | 2 +-
> > 1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/net/bluetooth/hci_event.c b/net/bluetooth/hci_event.c
> > index 7d0db1ca1248..f898fa42a183 100644
> > --- a/net/bluetooth/hci_event.c
> > +++ b/net/bluetooth/hci_event.c
> > @@ -4445,7 +4445,7 @@ static void hci_sync_conn_complete_evt(struct hci_dev *hdev,
> > {
> > 	struct hci_ev_sync_conn_complete *ev = (void *) skb->data;
> > 	struct hci_conn *conn;
> > -	unsigned int notify_evt;
> > +	unsigned int notify_evt = 0;
> >
> > 	BT_DBG("%s status 0x%2.2x", hdev->name, ev->status);
>
> lets modify the switch statement and add a default case. And then lets add a check to notify_evt != 0.
>
> With that in mind, I wonder if this is not better
>
>          /* Notify only in case of SCO over HCI transport data path which
>           * is zero and non-zero value shall be non-HCI transport data path
>           */
> 	if (conn->codec.data_path == 0 && hdev->notify) {
> 		switch (ev->air_mode) {
> 		case 0x02:
> 			hdev->notify(hdev, HCI_NOTIFY_ENABLE_SCO_CVSD);
> 			break;
> 		case 0x03:
> 			hdev->notify(hdev, HCI_NOTIFY_ENABLE_SCO_TRANSP);
> 			break;
> 		}
> 	}

I prefer this, because it is a restoration of earlier logic, rather than
changing his logic. I will resend a patch, thank you.

--
Jackie Liu

> Regards
>
> Marcel