From 960c7339de27c6d6fec13b54880501c3576bb08d Mon Sep 17 00:00:00 2001
From: Johan Hovold <johan@kernel.org>
Date: Mon, 21 Sep 2020 15:59:49 +0200
Subject: [PATCH] USB: cdc-acm: handle broken union descriptors
Git-commit: 960c7339de27c6d6fec13b54880501c3576bb08d
Patch-mainline: v5.10-rc1
References: git-fixes
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>
Acked-by: Takashi Iwai <tiwai@suse.de>
---
drivers/usb/class/cdc-acm.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 3b87e978d972..30137d1b0d8d 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1241,9 +1241,21 @@ 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) {
--
2.16.4