# CVE-2024-44956: drm/xe/preempt_fence: enlarge the fence critical section

CVE-2024-44956 is fixed in linux on 1 platform, first by DEBIAN-CVE-2024-44956, released September 4, 2024. It is not reported as exploited. Patch Radar priority: Routine.

- Web page: https://patchblox.com/security/cve/CVE-2024-44956
- Priority: Routine
- CVSS: 5.5 (medium)
- EPSS: 0.0014
- CISA KEV: not listed
- Exploited (vendor report): no
- Publicly disclosed: no
- Published: Sep 4, 2024
- Weakness: Improper Locking
- Vendor advisory: https://msrc.microsoft.com/update-guide/vulnerability/CVE-2024-44956

## Description

In the Linux kernel, the following vulnerability has been resolved:  drm/xe/preempt_fence: enlarge the fence critical section  It is really easy to introduce subtle deadlocks in preempt_fence_work_func() since we operate on single global ordered-wq for signalling our preempt fences behind the scenes, so even though we signal a particular fence, everything in the callback should be in the fence critical section, since blocking in the callback will prevent other published fences from signalling. If we enlarge the fence critical section to cover the entire callback, then lockdep should be able to understand this better, and complain if we grab a sensitive lock like vm->lock, which is also held when waiting on preempt fences.

## Where it's fixed

| Platform | Product | Fixed in | Fix | Released |
|---|---|---|---|---|
| Linux | linux Debian 13.5 (trixie) | 6.10.6-1 | [DEBIAN-CVE-2024-44956](https://patchblox.com/security/data/fix/linux/debian-cve-2024-44956.md) | Sep 4, 2024 |
| Linux | linux Debian 14 | 6.10.6-1 | [DEBIAN-CVE-2024-44956](https://patchblox.com/security/data/fix/linux/debian-cve-2024-44956.md) | Sep 4, 2024 |

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