archive_read_format_zip_seekable_bid(struct archive_read *a, int best_bid)
{
	struct zip *zip = (struct zip *)a->format->data;
	int64_t file_size, current_offset;
	const char *p;
	int i, tail;

	/* If someone has already bid more than 32, then avoid
	   trashing the look-ahead buffers with a seek. */
	if (best_bid > 32)
		return (-1);

	file_size = __archive_read_seek(a, 0, SEEK_END);
	if (file_size <= 0)
		return 0;

	/* Search last 16k of file for end-of-central-directory
	 * record (which starts with PK\005\006) */
	tail = (int)zipmin(1024 * 16, file_size);
	current_offset = __archive_read_seek(a, -tail, SEEK_END);
	if (current_offset < 0)
		return 0;
	if ((p = __archive_read_ahead(a, (size_t)tail, NULL)) == NULL)
		return 0;
	/* Boyer-Moore search backwards from the end, since we want
	 * to match the last EOCD in the file (there can be more than
	 * one if there is an uncompressed Zip archive as a member
	 * within this Zip archive). */
	for (i = tail - 22; i > 0;) {
		switch (p[i]) {
		case 'P':
			if (memcmp(p + i, "PK\005\006", 4) == 0) {
				int ret = read_eocd(zip, p + i,
				    current_offset + i);
				if (ret > 0) {
					/* Zip64 EOCD locator precedes
					 * regular EOCD if present. */
					if (i >= 20
					    && memcmp(p + i - 20, "PK\006\007", 4) == 0) {
						read_zip64_eocd(a, zip, p + i - 20);
					}
					return (ret);
				}
			}
			i -= 4;
			break;
		case 'K': i -= 1; break;
		case 005: i -= 2; break;
		case 006: i -= 3; break;
		default: i -= 4; break;
		}
	}
	return 0;
}

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.