struct iovec

https://elixir.bootlin.com/linux/v5.7/source/include/uapi/linux/uio.h#L17

struct iovec
{
	void __user *iov_base;	/* BSD uses caddr_t (1003.1g requires void *) */
	__kernel_size_t iov_len; /* Must be size_t (1003.1g) */
};