static void ffs_func_unbind(struct usb_configuration *c,
			    struct usb_function *f)
{
	struct ffs_function *func = ffs_func_from_usb(f);
	struct ffs_data *ffs = func->ffs;
	struct f_fs_opts *opts =
		container_of(f->fi, struct f_fs_opts, func_inst);
	struct ffs_ep *ep = func->eps;
	unsigned count = ffs->eps_count;
	unsigned long flags;

	ENTER();
	if (ffs->func == func) {
		ffs_func_eps_disable(func);
		ffs->func = NULL;
	}

	if (!--opts->refcnt)
		functionfs_unbind(ffs);

	/* cleanup after autoconfig */
	spin_lock_irqsave(&func->ffs->eps_lock, flags);
	do {
		if (ep->ep && ep->req)
			usb_ep_free_request(ep->ep, ep->req);
		ep->req = NULL;
		++ep;
	} while (--count);
	spin_unlock_irqrestore(&func->ffs->eps_lock, flags);
	kfree(func->eps);
	func->eps = NULL;
	/*
	 * eps, descriptors and interfaces_nums are allocated in the
	 * same chunk so only one free is required.
	 */
	func->function.fs_descriptors = NULL;
	func->function.hs_descriptors = NULL;
	func->function.ss_descriptors = NULL;
	func->interfaces_nums = NULL;

	ffs_event_add(ffs, FUNCTIONFS_UNBIND);
}

The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.