[PATCH] bluetooth: fix uninitialized variables notify_evt

[PATCH] bluetooth: fix uninitialized variables notify_evt

[Jackie Liu]

From: Jackie Liu <liuyun01@kylinos.cn>

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@kylinos.cn>
---
 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);
 
-- 
2.25.1

Re: [PATCH] bluetooth: fix uninitialized variables notify_evt

[Marcel Holtmann]

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@kylinos.cn>
> ---
> 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;
		}
	}

Regards

Marcel

Re: [PATCH] bluetooth: fix uninitialized variables notify_evt

[Jackie Liu]

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@kylinos.cn>
>> ---
>> 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
>