static int regulator_ena_gpio_request(struct regulator_dev *rdev,
				const struct regulator_config *config)
{
	struct regulator_enable_gpio *pin;
	struct gpio_desc *gpiod;
	int ret;

	gpiod = gpio_to_desc(config->ena_gpio);

	list_for_each_entry(pin, &regulator_ena_gpio_list, list) {
		if (pin->gpiod == gpiod) {
			rdev_dbg(rdev, "GPIO %d is already used\n",
				config->ena_gpio);
			goto update_ena_gpio_to_rdev;
		}
	}

	ret = gpio_request_one(config->ena_gpio,
				GPIOF_DIR_OUT | config->ena_gpio_flags,
				rdev_get_name(rdev));
	if (ret)
		return ret;

	pin = kzalloc(sizeof(struct regulator_enable_gpio), GFP_KERNEL);
	if (pin == NULL) {
		gpio_free(config->ena_gpio);
		return -ENOMEM;
	}

	pin->gpiod = gpiod;
	pin->ena_gpio_invert = config->ena_gpio_invert;
	list_add(&pin->list, &regulator_ena_gpio_list);

update_ena_gpio_to_rdev:
	pin->request_count++;
	rdev->ena_pin = pin;
	return 0;
}

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 Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.