Arch Linux: Denial of service (CVE-2022-0667)

In BIND 9.18.0 the recursive client code was refactored that introduced a "backstop lifetime timer". While BIND is processing a request for a DS record that needs to be forwarded, it waits until this processing is complete or until the backstop lifetime timer has timed out. When the resume_dslookup() function is called as a result of such a timeout, the function does not test whether the fetch has previously been shut down. This introduces the possibility of triggering an assertion failure, which could cause the BIND process to terminate.