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[2/4] USB: cdc-acm: handle broken union descriptors

Message ID 20200921113525.32187-3-johan@kernel.org (mailing list archive)
State Superseded
Headers show
Series USB: cdc-acm: handle broken union descriptors | expand

Commit Message

Johan Hovold Sept. 21, 2020, 11:35 a.m. UTC
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 is specifically makes the Whistler radio scanners TRX series
devices work with the driver without adding further quirks to the
device-id table.

Link: https://lore.kernel.org/r/5f4ca4f8.1c69fb81.a4487.0f5f@mx.google.com
Reported-by: Daniel Caujolle-Bert <f1rmb.daniel@gmail.com>
Signed-off-by: Johan Hovold <johan@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 e28ac640ff9c..5b1a1cd0168d 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1240,9 +1240,21 @@  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_warn(&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) {