netdev - [PATCH net] cdc_ether: Ignore bogus union descriptor for RNDIS devices

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Date:	Thu, 26 Apr 2012 12:55:03 +0200
From:	Bjørn Mork <bjorn@...k.no>
To:	netdev@...r.kernel.org
Cc:	linux-usb@...r.kernel.org,
	Bjørn Mork <bjorn@...k.no>,
	Markus Kolb <linux-201011@...er-net.de>,
	Iker Salmón San Millán 
	<shaola@...ebian.org>, Jonathan Nieder <jrnieder@...il.com>,
	Oliver Neukum <oliver@...kum.org>, 655387@...s.debian.org,
	stable@...r.kernel.org
Subject: [PATCH net] cdc_ether: Ignore bogus union descriptor for RNDIS devices

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@...er-net.de>
Cc: Iker Salmón San Millán <shaola@...ebian.org>
Cc: Jonathan Nieder <jrnieder@...il.com>
Cc: Oliver Neukum <oliver@...kum.org>
Cc: 655387@...s.debian.org
Cc: stable@...r.kernel.org
Signed-off-by: Bjørn Mork <bjorn@...k.no>
---
Something like this, then?

This has only been build tested by me as I don't have any of the affected
devices.  It would be great if any of the reporters could verify that it
solves the problem.  I can provide prebuilt modules for Debian 3.2 based
kernels to simplify the testing (just rmmod and insmod - no need to build
or boot).  Send me an email if you want the module.

Sorry for the long delay in following up this.  I totally forgot about it.


Bjørn

 drivers/net/usb/cdc_ether.c |   12 +++++++++++-
 1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/drivers/net/usb/cdc_ether.c b/drivers/net/usb/cdc_ether.c
index 90a3002..4ed5a38 100644
--- 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) {
@@ -271,8 +277,12 @@ 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) {
-- 
1.7.10

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