CVE-2026-64347

In the Linux kernel, the following vulnerability has been resolved:

usb: gadget: composite: fix dead empty check in the USB_DT_OTG handler

The OTG branch of composite_setup() falls back to the first

configuration when none is selected:

if (cdev->config)

config = cdev->config;

else

config = list_first_entry(&cdev->configs,

struct usb_configuration, list);

if (!config)

goto done;

...

memcpy(req->buf, config->descriptors[0], value);

list_first_entry() never returns NULL. On an empty list it returns

container_of() of the list head. So the "if (!config)" check is dead.

When cdev->configs is empty, config points at the head inside struct

usb_composite_dev. config->descriptors[0] reads whatever sits at that

offset. The memcpy copies up to w_length bytes of it into the response

buffer.

cdev->configs can be empty in two cases. One is a teardown race on

gadget unbind with a control transfer in flight. The other is a driver

that sets is_otg before it adds a config. A reproducer that holds

cdev->configs empty triggers a KASAN fault in this branch.

Use list_first_entry_or_null() so the existing check does its job.