# CVE-2022-42324: xen: Oxenstored 32->31 bit integer truncation issues Integers in Ocaml are 63 or 31 bits of signed precision

CVE-2022-42324 is fixed in xen on 1 platform, first by DEBIAN-CVE-2022-42324, released November 1, 2022. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2022-42324
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0030
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Nov 1, 2022

## Description

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.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | xen Debian 12.15 (bookworm) | 4.16.2+90-g0d39a6d1ae-1 | [DEBIAN-CVE-2022-42324](https://patchblox.com/security/data/fix/linux/debian-cve-2022-42324.md) | Nov 1, 2022 |
| Linux | xen Debian 13.5 (trixie) | 4.16.2+90-g0d39a6d1ae-1 | [DEBIAN-CVE-2022-42324](https://patchblox.com/security/data/fix/linux/debian-cve-2022-42324.md) | Nov 1, 2022 |
| Linux | xen Debian 14 | 4.16.2+90-g0d39a6d1ae-1 | [DEBIAN-CVE-2022-42324](https://patchblox.com/security/data/fix/linux/debian-cve-2022-42324.md) | Nov 1, 2022 |

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