Re: [PATCH net,stable] qmi_wwan: do not steal interfaces from class drivers

[David Miller]

From: Bjørn Mork 
Date: Wed,  2 May 2018 22:22:54 +0200

> The USB_DEVICE_INTERFACE_NUMBER matching macro assumes that
> the { vendorid, productid, interfacenumber } set uniquely
> identifies one specific function.  This has proven to fail
> for some configurable devices. One example is the Quectel
> EM06/EP06 where the same interface number can be either
> QMI or MBIM, without the device ID changing either.
> 
> Fix by requiring the vendor-specific class for interface number
> based matching.  Functions of other classes can and should use
> class based matching instead.
> 
> Fixes: 03304bcb5ec4 ("net: qmi_wwan: use fixed interface number matching")
> Signed-off-by: Bjørn Mork 
> ---
> It's quite possible that the fix should be integrated in the
> USB_DEVICE_INTERFACE_NUMBER macro instead.  But that has grown a few
> other users since it was added, so changing it now seems risky. 
> Another option is of course adding a new match macro with the
> USB_CLASS_VENDOR_SPEC match integrated. Maybe best?
> 
> But I'm proposing this as-is for now, since this quickfix seems most
> suitable for stable backporting.

Yes, this simpler approache is better for net and -stable.

Applied.

If you want to do something more sophisticated, that can be done
in net-next.

Thanks.

[PATCH net,stable] qmi_wwan: do not steal interfaces from class drivers

[Bjørn Mork]

The USB_DEVICE_INTERFACE_NUMBER matching macro assumes that
the { vendorid, productid, interfacenumber } set uniquely
identifies one specific function.  This has proven to fail
for some configurable devices. One example is the Quectel
EM06/EP06 where the same interface number can be either
QMI or MBIM, without the device ID changing either.

Fix by requiring the vendor-specific class for interface number
based matching.  Functions of other classes can and should use
class based matching instead.

Fixes: 03304bcb5ec4 ("net: qmi_wwan: use fixed interface number matching")
Signed-off-by: Bjørn Mork 
---
It's quite possible that the fix should be integrated in the
USB_DEVICE_INTERFACE_NUMBER macro instead.  But that has grown a few
other users since it was added, so changing it now seems risky. 
Another option is of course adding a new match macro with the
USB_CLASS_VENDOR_SPEC match integrated. Maybe best?

But I'm proposing this as-is for now, since this quickfix seems most
suitable for stable backporting.

 drivers/net/usb/qmi_wwan.c | 12 
 1 file changed, 12 insertions(+)

diff --git a/drivers/net/usb/qmi_wwan.c b/drivers/net/usb/qmi_wwan.c
index 51c68fc416fa..42565dd33aa6 100644
--- a/drivers/net/usb/qmi_wwan.c
+++ b/drivers/net/usb/qmi_wwan.c
@@ -1344,6 +1344,18 @@ static int qmi_wwan_probe(struct usb_interface *intf,
id->driver_info = (unsigned long)_wwan_info;
}
 
+   /* There are devices where the same interface number can be
+* configured as different functions. We should only bind to
+* vendor specific functions when matching on interface number
+*/
+   if (id->match_flags & USB_DEVICE_ID_MATCH_INT_NUMBER &&
+   desc->bInterfaceClass != USB_CLASS_VENDOR_SPEC) {
+   dev_dbg(>dev,
+   "Rejecting interface number match for class %02x\n",
+   desc->bInterfaceClass);
+   return -ENODEV;
+   }
+
/* Quectel EC20 quirk where we've QMI on interface 4 instead of 0 */
if (quectel_ec20_detected(intf) && desc->bInterfaceNumber == 0) {
dev_dbg(>dev, "Quectel EC20 quirk, skipping interface 
0\n");
-- 
2.11.0