REDHAT-BUG-2479808: Use After Free

Use After Free vulnerability in the DNSSEC validator of the Unbound DNS resolver. The flaw is caused by a struct-assignment bug during deep-copying of response messages when DS sub-queries need to suspend validation due to NSEC3 computational budget exhaustion (introduced in Unbound 1.19.1). The deep-copy operation overwrites the destination's rrsets pointer with the source's pointer. After the sub-query region is freed, the resumed validator dereferences this dangling pointer, triggering a crash or potentially enabling arbitrary code execution. An adversary can exploit this vulnerability by controlling a malicious DNSSEC-signed zone and querying a vulnerable Unbound instance.