# CVE-2026-90244: iommu/dma: Restore locking around msi_page_list

> A race condition in the Linux kernel IOMMU DMA subsystem allows concurrent MSI allocation to corrupt memory, potentially leading to system crashes or code execution.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 17 Sep 2026
- **Updated:** 19 Oct 2026
- **Also known as:** BELL-CVE-2026-90244, DEBIAN-CVE-2026-90244, GHSA-rjf9-x7mr-46ph, UBUNTU-CVE-2026-90244

## What is CVE-2026-90244?

CVE-2026-90244 is a high-severity vulnerability in Linux, published on 17 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

In the Linux kernel, the following vulnerability has been resolved:

iommu/dma: Restore locking around msi_page_list

Unlike a group's default domain, which is always freshly allocated
and privately owned (iommu_group_alloc_default_domain()), VFIO type1's
legacy container merges any newly attached group into an existing
domain whenever their iommu_ops and cache-coherency enforcement match.

iommu_dma_get_msi_page() only asserts the caller's own group mutex is
held (iommu_group_mutex_assert()). On an IOMMU that publishes
IOMMU_RESV_SW_MSI, e.g. ARM SMMU, a VM with two such devices assigned
through the legacy container can have their guest drivers probe and
allocate MSIs in parallel; each host-side VFIO_DEVICE_SET_IRQS lands
on a different device fd and group mutex, but both devices' domains
are the same merged domain, so both can enter
iommu_dma_get_msi_page() concurrently and corrupt msi_page_list.

commit 288683c92b1a ("iommu: Make iommu_dma_prepare_msi() into a
generic operation") dropped the prior msi_prepare_lock on the
reasoning that "each iommu_domain is unique to a group," which holds
for default domains but not this VFIO type1 case. Restore the static
lock, since it's only guarding a corner case and will likely never
be contended.

iommufd avoids the equivalent problem by having its own callers
(iommufd_sw_map_msi()) take a ctx-wide sw_msi_lock before ever
reaching the shared list. VFIO type1 can't mirror that since it
dispatches to iommu_dma_sw_msi() which is outside VFIO's jurisdiction.

## Which versions are affected by CVE-2026-90244?


## How do I fix CVE-2026-90244?

Apply the vendor's patch.

## Is CVE-2026-90244 being exploited?

There is no known exploitation of CVE-2026-90244 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-90244 and fix it if it is affected.

What it is: CVE-2026-90244 is a high-severity vulnerability in Linux, published on 17 Sep 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-90244 in the wild and no public exploit code.

Affected product: Linux. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-90244/ (Markdown: https://insights.sbomify.com/CVE-2026-90244/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-90244
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-90244
- OSV: https://osv.dev/vulnerability/CVE-2026-90244

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-90244/
Summaries are generated and may contain mistakes; the official description above is the record.