[patch] HID: hid-logitech-dj: add some range checks

[patch] HID: hid-logitech-dj: add some range checks

[Dan Carpenter]

We can't trust dj_report->device_index because it comes from the
user and hasn't been range checked.  It is used as an offset into
the djrcv_dev->paired_dj_devices[] array which has 7 elements.
There is one range check already in logi_dj_recv_add_djhid_device()
and I have copy and pasted that here.

DJ_DEVICE_INDEX_MIN is 1.
DJ_DEVICE_INDEX_MAX is 6.

Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
---
This is a static checker fix and I'm not certain it's correct,
please look it over carefully.

I do not know this code well, so I don't know why a zero index is
invalid.

diff --git a/drivers/hid/hid-logitech-dj.c b/drivers/hid/hid-logitech-dj.c
index 9500f2f..c01cd25 100644
--- a/drivers/hid/hid-logitech-dj.c
+++ b/drivers/hid/hid-logitech-dj.c
@@ -701,6 +701,13 @@ static int logi_dj_raw_event(struct hid_device *hdev,
 	 * anything else with it.
 	 */
 
+	if ((dj_report->device_index < DJ_DEVICE_INDEX_MIN) ||
+	    (dj_report->device_index > DJ_DEVICE_INDEX_MAX)) {
+		dev_err(&hdev->dev, "%s: invalid device index:%d\n", __func__,
+			dj_report->device_index);
+		return true;
+	}
+
 	spin_lock_irqsave(&djrcv_dev->lock, flags);
 	if (dj_report->report_id == REPORT_ID_DJ_SHORT) {
 		switch (dj_report->report_type) {

Re: [patch] HID: hid-logitech-dj: add some range checks

[Benjamin Tissoires]

Hi Dan,

On Tue, Mar 5, 2013 at 2:06 PM, Dan Carpenter <dan.carpenter@oracle.com> wrote:
> We can't trust dj_report->device_index because it comes from the
> user and hasn't been range checked.  It is used as an offset into
> the djrcv_dev->paired_dj_devices[] array which has 7 elements.
> There is one range check already in logi_dj_recv_add_djhid_device()
> and I have copy and pasted that here.
>
> DJ_DEVICE_INDEX_MIN is 1.
> DJ_DEVICE_INDEX_MAX is 6.
>
> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
> ---
> This is a static checker fix and I'm not certain it's correct,
> please look it over carefully.
>
> I do not know this code well, so I don't know why a zero index is
> invalid.
>
> diff --git a/drivers/hid/hid-logitech-dj.c b/drivers/hid/hid-logitech-dj.c
> index 9500f2f..c01cd25 100644
> --- a/drivers/hid/hid-logitech-dj.c
> +++ b/drivers/hid/hid-logitech-dj.c
> @@ -701,6 +701,13 @@ static int logi_dj_raw_event(struct hid_device *hdev,
>          * anything else with it.
>          */
>
> +       if ((dj_report->device_index < DJ_DEVICE_INDEX_MIN) ||
> +           (dj_report->device_index > DJ_DEVICE_INDEX_MAX)) {
> +               dev_err(&hdev->dev, "%s: invalid device index:%d\n", __func__,
> +                       dj_report->device_index);
> +               return true;
> +       }
> +

Sorry, but it's a NACK in its current form:
- device_index == 0 is the receiver. IIRC, the receiver sends the
different REPORT_TYPE_NOTIF_*. So I would say that this patch blocks
events from the receiver.
- the DJ protocol specifies that the device index is between 1 and 6
and that 0 means the receiver. So unless there is a problem in the USB
line from the receiver to the driver, device index will be between 1
and 6 for input events. This is only true as long as with stay with
real firmware from Logitech, not from events from uhid.

If you want to add a check, it need to be in logi_dj_recv_forward_report().
The current access to djrcv_dev->paired_dj_devices[] in
delayedwork_callback() has been removed in latest HID tree:
https://git.kernel.org/cgit/linux/kernel/git/jikos/hid.git/log/?h=for-3.10/logitech

Cheers,
Benjamin

>         spin_lock_irqsave(&djrcv_dev->lock, flags);
>         if (dj_report->report_id == REPORT_ID_DJ_SHORT) {
>                 switch (dj_report->report_type) {
> --
> To unsubscribe from this list: send the line "unsubscribe linux-input" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [patch] HID: hid-logitech-dj: add some range checks

[Nestor Lopez Casado]

Hi Dan,


On Tue, Mar 5, 2013 at 3:47 PM, Benjamin Tissoires
<benjamin.tissoires@gmail.com> wrote:
> Hi Dan,
>
> On Tue, Mar 5, 2013 at 2:06 PM, Dan Carpenter <dan.carpenter@oracle.com> wrote:
>> We can't trust dj_report->device_index because it comes from the
>> user and hasn't been range checked.  It is used as an offset into
>> the djrcv_dev->paired_dj_devices[] array which has 7 elements.
>> There is one range check already in logi_dj_recv_add_djhid_device()
>> and I have copy and pasted that here.
>>
>> DJ_DEVICE_INDEX_MIN is 1.
>> DJ_DEVICE_INDEX_MAX is 6.
>>
>> Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
>> ---
>> This is a static checker fix and I'm not certain it's correct,
>> please look it over carefully.
>>
>> I do not know this code well, so I don't know why a zero index is
>> invalid.
>>
>> diff --git a/drivers/hid/hid-logitech-dj.c b/drivers/hid/hid-logitech-dj.c
>> index 9500f2f..c01cd25 100644
>> --- a/drivers/hid/hid-logitech-dj.c
>> +++ b/drivers/hid/hid-logitech-dj.c
>> @@ -701,6 +701,13 @@ static int logi_dj_raw_event(struct hid_device *hdev,
>>          * anything else with it.
>>          */
>>
>> +       if ((dj_report->device_index < DJ_DEVICE_INDEX_MIN) ||
>> +           (dj_report->device_index > DJ_DEVICE_INDEX_MAX)) {
>> +               dev_err(&hdev->dev, "%s: invalid device index:%d\n", __func__,
>> +                       dj_report->device_index);
>> +               return true;
>> +       }
>> +
>
> Sorry, but it's a NACK in its current form:
> - device_index == 0 is the receiver. IIRC, the receiver sends the
> different REPORT_TYPE_NOTIF_*. So I would say that this patch blocks
> events from the receiver.
Correct. This would block notifications from the receiver.

> - the DJ protocol specifies that the device index is between 1 and 6
> and that 0 means the receiver. So unless there is a problem in the USB
> line from the receiver to the driver, device index will be between 1
> and 6 for input events. This is only true as long as with stay with
> real firmware from Logitech, not from events from uhid.
>
> If you want to add a check, it need to be in logi_dj_recv_forward_report().
> The current access to djrcv_dev->paired_dj_devices[] in
> delayedwork_callback() has been removed in latest HID tree:
> https://git.kernel.org/cgit/linux/kernel/git/jikos/hid.git/log/?h=for-3.10/logitech
The test could be added there. It would be quite defensive though, as
we should always get the right device indexes.
>
> Cheers,
> Benjamin
>
>>         spin_lock_irqsave(&djrcv_dev->lock, flags);
>>         if (dj_report->report_id == REPORT_ID_DJ_SHORT) {
>>                 switch (dj_report->report_type) {
>> --
>> To unsubscribe from this list: send the line "unsubscribe linux-input" in
>> the body of a message to majordomo@vger.kernel.org
>> More majordomo info at  http://vger.kernel.org/majordomo-info.html
> --
> To unsubscribe from this list: send the line "unsubscribe linux-input" in
> the body of a message to majordomo@vger.kernel.org
> More majordomo info at  http://vger.kernel.org/majordomo-info.html

Re: [patch] HID: hid-logitech-dj: add some range checks

[Dan Carpenter]

On Tue, Mar 05, 2013 at 05:34:08PM +0100, Nestor Lopez Casado wrote:
> > If you want to add a check, it need to be in logi_dj_recv_forward_report().
> > The current access to djrcv_dev->paired_dj_devices[] in
> > delayedwork_callback() has been removed in latest HID tree:
> > https://git.kernel.org/cgit/linux/kernel/git/jikos/hid.git/log/?h=for-3.10/logitech
> The test could be added there. It would be quite defensive though, as
> we should always get the right device indexes.


Ah...  I appologize for the noise.  I misunderstood how
hid_input_report() works.  I thought it could be called with user
supplied parameters.

Never mind.

regards,
dan carpenter