[PATCH 6.1 197/236] usb: gadget: composite: fix OS descriptors w_value logic

Greg Kroah-Hartman
2024-05-14T11:36:47Z

From: Peter Korsgaard <peter@korsgaard.com>

commit ec6ce7075ef879b91a8710829016005dc8170f17 upstream.

The OS descriptors logic had the high/low byte of w_value inverted, causing
the extended properties to not be accessible for interface != 0.

>From the Microsoft documentation:
https://learn.microsoft.com/en-us/windows-hardware/drivers/usbcon/microsoft-os-1-0-descriptors-specification

OS_Desc_CompatID.doc (w_index = 0x4):

- wValue:

High Byte = InterfaceNumber. InterfaceNumber is set to the number of the
interface or function that is associated with the descriptor, typically
0x00. Because a device can have only one extended compat ID descriptor,
it should ignore InterfaceNumber, regardless of the value, and simply
return the descriptor.

Low Byte = 0. PageNumber is used to retrieve descriptors that are larger
than 64 KB. The header section is 16 bytes, so PageNumber is set to 0 for
this request.

We currently do not support >64KB compat ID descriptors, so verify that the
low byte is 0.

OS_Desc_Ext_Prop.doc (w_index = 0x5):

- wValue:

High byte = InterfaceNumber. The high byte of wValue is set to the number
of the interface or function that is associated with the descriptor.

Low byte = PageNumber. The low byte of wValue is used to retrieve
descriptors that are larger than 64 KB. The header section is 10 bytes, so
PageNumber is set to 0 for this request.

We also don't support >64KB extended properties, so verify that the low byte
is 0 and use the high byte for the interface number.

Fixes: 37a3a533429e ("usb: gadget: OS Feature Descriptors support")
Cc: stable <stable@kernel.org>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Link: https://lore.kernel.org/r/20240404100635.3215340-1-peter@korsgaard.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/usb/gadget/composite.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/drivers/usb/gadget/composite.c
+++ b/drivers/usb/gadget/composite.c
@@ -1993,7 +1993,7 @@ unknown:
buf[5] = 0x01;
switch (ctrl->bRequestType & USB_RECIP_MASK) {
case USB_RECIP_DEVICE:
- if (w_index != 0x4 || (w_value >> 8))
+ if (w_index != 0x4 || (w_value & 0xff))
break;
buf[6] = w_index;
/* Number of ext compat interfaces */
@@ -2009,9 +2009,9 @@ unknown:
}
break;
case USB_RECIP_INTERFACE:
- if (w_index != 0x5 || (w_value >> 8))
+ if (w_index != 0x5 || (w_value & 0xff))
break;
- interface = w_value & 0xFF;
+ interface = w_value >> 8;
if (interface >= MAX_CONFIG_INTERFACES ||
!os_desc_cfg->interface[interface])
break;