int csum_partial_copy_fromiovecend(unsigned char *kdata, struct iovec *iov,
				 int offset, unsigned int len, __wsum *csump)
{
	__wsum csum = *csump;
	int partial_cnt = 0, err = 0;

	/* Skip over the finished iovecs */
	while (offset >= iov->iov_len) {
		offset -= iov->iov_len;
		iov++;
	}

	while (len > 0) {
		u8 __user *base = iov->iov_base + offset;
		int copy = min_t(unsigned int, len, iov->iov_len - offset);

		offset = 0;

		/* There is a remnant from previous iov. */
		if (partial_cnt) {
			int par_len = 4 - partial_cnt;

			/* iov component is too short ... */
			if (par_len > copy) {
				if (copy_from_user(kdata, base, copy))
					goto out_fault;
				kdata += copy;
				base += copy;
				partial_cnt += copy;
				len -= copy;
				iov++;
				if (len)
					continue;
				*csump = csum_partial(kdata - partial_cnt,
							 partial_cnt, csum);
				goto out;
			}
			if (copy_from_user(kdata, base, par_len))
				goto out_fault;
			csum = csum_partial(kdata - partial_cnt, 4, csum);
			kdata += par_len;
			base  += par_len;
			copy  -= par_len;
			len   -= par_len;
			partial_cnt = 0;
		}

		if (len > copy) {
			partial_cnt = copy % 4;
			if (partial_cnt) {
				copy -= partial_cnt;
				if (copy_from_user(kdata + copy, base + copy,
						partial_cnt))
					goto out_fault;
			}
		}

		if (copy) {
			csum = csum_and_copy_from_user(base, kdata, copy,
							csum, &err);
			if (err)
				goto out;
		}
		len   -= copy + partial_cnt;
		kdata += copy + partial_cnt;
		iov++;
	}
	*csump = csum;
out:
	return err;

out_fault:
	err = -EFAULT;
	goto out;
}

The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.