CID 316511: Insecure data handling (TAINTED_SCALAR)

*** CID 316511:  Insecure data handling  (TAINTED_SCALAR)
/lib/dns/rdata/generic/hip_55.c: 496 in casecompare_hip()
490     	key_len = uint16_fromregion(&r1);
491     	isc_region_consume(&r1, 2); /* key length */
492     	isc_region_consume(&r2, 4);
493     
494     	INSIST(r1.length >= (unsigned)(hit_len + key_len));
495     	INSIST(r2.length >= (unsigned)(hit_len + key_len));
>>>     CID 316511:  Insecure data handling  (TAINTED_SCALAR)
>>>     Passing tainted expression "hit_len + key_len" to "memcmp", which uses it as an offset.
496     	order = memcmp(r1.base, r2.base, hit_len + key_len);
497     	if (order != 0) {
498     		return (order);
499     	}
500     	isc_region_consume(&r1, hit_len + key_len);
501     	isc_region_consume(&r2, hit_len + key_len);