archive_read_format_iso9660_bid(struct archive_read *a, int best_bid)
{
	struct iso9660 *iso9660;
	ssize_t bytes_read;
	const unsigned char *p;
	int seenTerminator;

	/* If there's already a better bid than we can ever
	   make, don't bother testing. */
	if (best_bid > 48)
		return (-1);

	iso9660 = (struct iso9660 *)(a->format->data);

	/*
	 * Skip the first 32k (reserved area) and get the first
	 * 8 sectors of the volume descriptor table.  Of course,
	 * if the I/O layer gives us more, we'll take it.
	 */
#define RESERVED_AREA	(SYSTEM_AREA_BLOCK * LOGICAL_BLOCK_SIZE)
	p = __archive_read_ahead(a,
	    RESERVED_AREA + 8 * LOGICAL_BLOCK_SIZE,
	    &bytes_read);
	if (p == NULL)
	    return (-1);

	/* Skip the reserved area. */
	bytes_read -= RESERVED_AREA;
	p += RESERVED_AREA;

	/* Check each volume descriptor. */
	seenTerminator = 0;
	for (; bytes_read > LOGICAL_BLOCK_SIZE;
	    bytes_read -= LOGICAL_BLOCK_SIZE, p += LOGICAL_BLOCK_SIZE) {
		/* Do not handle undefined Volume Descriptor Type. */
		if (p[0] >= 4 && p[0] <= 254)
			return (0);
		/* Standard Identifier must be "CD001" */
		if (memcmp(p + 1, "CD001", 5) != 0)
			return (0);
		if (isPVD(iso9660, p))
			continue;
		if (!iso9660->joliet.location) {
			if (isJolietSVD(iso9660, p))
				continue;
		}
		if (isBootRecord(iso9660, p))
			continue;
		if (isEVD(iso9660, p))
			continue;
		if (isSVD(iso9660, p))
			continue;
		if (isVolumePartition(iso9660, p))
			continue;
		if (isVDSetTerminator(iso9660, p)) {
			seenTerminator = 1;
			break;
		}
		return (0);
	}
	/*
	 * ISO 9660 format must have Primary Volume Descriptor and
	 * Volume Descriptor Set Terminator.
	 */
	if (seenTerminator && iso9660->primary.location > 16)
		return (48);

	/* We didn't find a valid PVD; return a bid of zero. */
	return (0);
}

The product performs a calculation that can produce an integer overflow or wraparound when the logic assumes that the resulting value will always be larger than the original value. This occurs when an integer value is incremented to a value that is too large to store in the associated representation. When this occurs, the value may become a very small or negative number.