cdc_ether: Ignore bogus union descriptor for RNDIS devices

commit 6eddcb4c82883451aec3be1240f17793370fa62f upstream.

Some RNDIS devices include a bogus CDC Union descriptor pointing
to non-existing interfaces.  The RNDIS code is already prepared
to handle devices without a CDC Union descriptor by hardwiring
the driver to use interfaces 0 and 1, which is correct for the
devices with the bogus descriptor as well. So we can reuse the
existing workaround.

Cc: Markus Kolb <linux-201011@tower-net.de>
Cc: Iker Salmón San Millán <shaola@esdebian.org>
Cc: Jonathan Nieder <jrnieder@gmail.com>
Cc: Oliver Neukum <oliver@neukum.org>
Cc: 655387@bugs.debian.org
Signed-off-by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/net/usb/cdc_ether.c b/drivers/net/usb/cdc_ether.c
index 4fd4144..eac4886 100644 (file)
--- a/drivers/net/usb/cdc_ether.c
+++ b/drivers/net/usb/cdc_ether.c
@@ -83,6 +83,7 @@ int usbnet_generic_cdc_bind(struct usbnet *dev, struct usb_interface *intf)
        struct cdc_state                *info = (void *) &dev->data;
        int                             status;
        int                             rndis;
+       bool                            android_rndis_quirk = false;
        struct usb_driver               *driver = driver_of(intf);
        struct usb_cdc_mdlm_desc        *desc = NULL;
        struct usb_cdc_mdlm_detail_desc *detail = NULL;
@@ -195,6 +196,11 @@ int usbnet_generic_cdc_bind(struct usbnet *dev, struct usb_interface *intf)
                                        info->control,
                                        info->u->bSlaveInterface0,
                                        info->data);
+                               /* fall back to hard-wiring for RNDIS */
+                               if (rndis) {
+                                       android_rndis_quirk = true;
+                                       goto next_desc;
+                               }
                                goto bad_desc;
                        }
                        if (info->control != intf) {
@@ -271,11 +277,15 @@ next_desc:
        /* Microsoft ActiveSync based and some regular RNDIS devices lack the
         * CDC descriptors, so we'll hard-wire the interfaces and not check
         * for descriptors.
+        *
+        * Some Android RNDIS devices have a CDC Union descriptor pointing
+        * to non-existing interfaces.  Ignore that and attempt the same
+        * hard-wired 0 and 1 interfaces.
         */
-       if (rndis && !info->u) {
+       if (rndis && (!info->u || android_rndis_quirk)) {
                info->control = usb_ifnum_to_if(dev->udev, 0);
                info->data = usb_ifnum_to_if(dev->udev, 1);
-               if (!info->control || !info->data) {
+               if (!info->control || !info->data || info->control != intf) {
                        dev_dbg(&intf->dev,
                                "rndis: master #0/%p slave #1/%p\n",
                                info->control,