CVE-2022-42324

Oxenstored 32->31 bit integer truncation issues Integers in Ocaml are 63 or
31 bits of signed precision. The Ocaml Xenbus library takes a C uint32_t
out of the ring and casts it directly to an Ocaml integer. In 64-bit Ocaml
builds this is fine, but in 32-bit builds, it truncates off the most
significant bit, and then creates unsigned/signed confusion in the
remainder. This in turn can feed a negative value into logic not expecting
a negative value, resulting in unexpected exceptions being thrown. The
unexpected exception is not handled suitably, creating a busy-loop trying
(and failing) to take the bad packet out of the xenstore ring.

Notes