diff mbox series

[4.14,164/191] USB: cdc-acm: handle broken union descriptors

Message ID 20201027134917.611618996@linuxfoundation.org
State Superseded
Headers show
Series None | expand

Commit Message

Greg Kroah-Hartman Oct. 27, 2020, 1:50 p.m. UTC 
From: Johan Hovold <johan@kernel.org>

[ Upstream commit 960c7339de27c6d6fec13b54880501c3576bb08d ]

Handle broken union functional descriptors where the master-interface
doesn't exist or where its class is of neither Communication or Data
type (as required by the specification) by falling back to
"combined-interface" probing.

Note that this still allows for handling union descriptors with switched
interfaces.

This specifically makes the Whistler radio scanners TRX series devices
work with the driver without adding further quirks to the device-id
table.

Reported-by: Daniel Caujolle-Bert <f1rmb.daniel@gmail.com>
Tested-by: Daniel Caujolle-Bert <f1rmb.daniel@gmail.com>
Acked-by: Oliver Neukum <oneukum@suse.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20200921135951.24045-3-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 drivers/usb/class/cdc-acm.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)
diff mbox series

Patch

diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index b3e4b014a1cc0..dff9860213624 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1287,9 +1287,21 @@  static int acm_probe(struct usb_interface *intf,
 			}
 		}
 	} else {
+		int class = -1;
+
 		data_intf_num = union_header->bSlaveInterface0;
 		control_interface = usb_ifnum_to_if(usb_dev, union_header->bMasterInterface0);
 		data_interface = usb_ifnum_to_if(usb_dev, data_intf_num);
+
+		if (control_interface)
+			class = control_interface->cur_altsetting->desc.bInterfaceClass;
+
+		if (class != USB_CLASS_COMM && class != USB_CLASS_CDC_DATA) {
+			dev_dbg(&intf->dev, "Broken union descriptor, assuming single interface\n");
+			combined_interfaces = 1;
+			control_interface = data_interface = intf;
+			goto look_for_collapsed_interface;
+		}
 	}
 
 	if (!control_interface || !data_interface) {