# CVE-2022-26356: xen: Racy interactions between dirty vram tracking and paging log dirty hypercalls Activation of log dirty mode done by XE...

CVE-2022-26356 is fixed in xen on 1 platform, first by DEBIAN-CVE-2022-26356, released April 5, 2022. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2022-26356
- Priority: Routine
- CVSS: 5.6 (medium)
- EPSS: 0.0024
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Apr 5, 2022

## Description

Racy interactions between dirty vram tracking and paging log dirty hypercalls Activation of log dirty mode done by XEN_DMOP_track_dirty_vram (was named HVMOP_track_dirty_vram before Xen 4.9) is racy with ongoing log dirty hypercalls. A suitably timed call to XEN_DMOP_track_dirty_vram can enable log dirty while another CPU is still in the process of tearing down the structures related to a previously enabled log dirty mode (XEN_DOMCTL_SHADOW_OP_OFF). This is due to lack of mutually exclusive locking between both operations and can lead to entries being added in already freed slots, resulting in a memory leak.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | xen Debian 12.15 (bookworm) | 4.16.1-1 | [DEBIAN-CVE-2022-26356](https://patchblox.com/security/data/fix/linux/debian-cve-2022-26356.md) | Apr 5, 2022 |
| Linux | xen Debian 13.5 (trixie) | 4.16.1-1 | [DEBIAN-CVE-2022-26356](https://patchblox.com/security/data/fix/linux/debian-cve-2022-26356.md) | Apr 5, 2022 |
| Linux | xen Debian 14 | 4.16.1-1 | [DEBIAN-CVE-2022-26356](https://patchblox.com/security/data/fix/linux/debian-cve-2022-26356.md) | Apr 5, 2022 |

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