CID 316509: Untrusted value as argument (TAINTED_SCALAR)

*** CID 316509:    (TAINTED_SCALAR)
/lib/dns/rdata/generic/nsec3_50.c: 312 in tostruct_nsec3()
306     	if (nsec3->salt == NULL) {
307     		return (ISC_R_NOMEMORY);
308     	}
309     	isc_region_consume(&region, nsec3->salt_length);
310     
311     	nsec3->next_length = uint8_consume_fromregion(&region);
>>>     CID 316509:    (TAINTED_SCALAR)
>>>     Passing tainted expression "nsec3->next_length" to "mem_maybedup", which uses it as an offset.
312     	nsec3->next = mem_maybedup(mctx, region.base, nsec3->next_length);
313     	if (nsec3->next == NULL) {
314     		goto cleanup;
315     	}
316     	isc_region_consume(&region, nsec3->next_length);
317     
/lib/dns/rdata/generic/nsec3_50.c: 305 in tostruct_nsec3()
299     	region.length = rdata->length;
300     	nsec3->hash = uint8_consume_fromregion(&region);
301     	nsec3->flags = uint8_consume_fromregion(&region);
302     	nsec3->iterations = uint16_consume_fromregion(&region);
303     
304     	nsec3->salt_length = uint8_consume_fromregion(&region);
>>>     CID 316509:    (TAINTED_SCALAR)
>>>     Passing tainted expression "nsec3->salt_length" to "mem_maybedup", which uses it as an offset.
305     	nsec3->salt = mem_maybedup(mctx, region.base, nsec3->salt_length);
306     	if (nsec3->salt == NULL) {
307     		return (ISC_R_NOMEMORY);
308     	}
309     	isc_region_consume(&region, nsec3->salt_length);
310