This is a note to let you know that I've just added the patch titled
USB: cdc-acm: handle broken union descriptors
to the 5.8-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
usb-cdc-acm-handle-broken-union-descriptors.patch
and it can be found in the queue-5.8 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 35a8acf48453f46bf5b28a602f3fb56eb7bf5aeb
Author: Johan Hovold <johan@xxxxxxxxxx>
Date: Mon Sep 21 15:59:49 2020 +0200
USB: cdc-acm: handle broken union descriptors
[ 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@xxxxxxxxx>
Tested-by: Daniel Caujolle-Bert <f1rmb.daniel@xxxxxxxxx>
Acked-by: Oliver Neukum <oneukum@xxxxxxxx>
Signed-off-by: Johan Hovold <johan@xxxxxxxxxx>
Link: https://lore.kernel.org/r/20200921135951.24045-3-johan@xxxxxxxxxx
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/drivers/usb/class/cdc-acm.c b/drivers/usb/class/cdc-acm.c
index 7499ba118665a..c02488d469185 100644
--- a/drivers/usb/class/cdc-acm.c
+++ b/drivers/usb/class/cdc-acm.c
@@ -1243,9 +1243,21 @@ 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) {
