# CVE-2026-68347: iommu/amd: Fix IRQ unsafe locking in gdom allocation

> A locking order violation in the AMD IOMMU driver can cause a kernel deadlock or crash, leading to denial of service.

- **Severity:** Not scored
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Not stated
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Aug 2026
- **Updated:** 17 Aug 2026
- **Also known as:** DEBIAN-CVE-2026-68347, GHSA-q9gw-ch4p-mf89, UBUNTU-CVE-2026-68347

## What is CVE-2026-68347?

CVE-2026-68347 is a vulnerability in Linux, published on 10 Aug 2026. 

### Official description

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

iommu/amd: Fix IRQ unsafe locking in gdom allocation

Lockdep complains:

  [  259.410489] =====================================================
  [  259.417287] WARNING: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected
  [  259.424667] 7.0.0-g51db1d8d2113 #54 Not tainted
  [  259.429718] -----------------------------------------------------
  [  259.436516] qemu-system-x86/10143 [HC0[0]:SC0[0]:HE0:SE1] is trying to acquire:
  [  259.444670] ff3b2b1c60305170 (&xa->xa_lock#25){+.+.}-{3:3}, at: __domain_flush_pages+0x17c/0x4b0
  [  259.454485]
                 and this task is already holding:
  [  259.460991] ff3b2b1c98504cc0 (&domain->lock){-.-.}-{3:3}, at: amd_iommu_iotlb_sync+0x25/0x60
  [  259.470408] which would create a new lock dependency:
  [  259.476041]  (&domain->lock){-.-.}-{3:3} -> (&xa->xa_lock#25){+.+.}-{3:3}
  [  259.483615]
                 but this new dependency connects a HARDIRQ-irq-safe lock:
  [  259.492447]  (&domain->lock){-.-.}-{3:3}
  [  259.492449]
                 ... which became HARDIRQ-irq-safe at:
  [  259.503705]   lock_acquire+0xb6/0x2e0
  [  259.507790]   _raw_spin_lock_irqsave+0x3e/0x60
  [  259.512748]   amd_iommu_flush_iotlb_all+0x20/0x50
  [  259.517996]   iommu_dma_free_iova.isra.0+0x1b8/0x1e0
  [  259.523534]   __iommu_dma_unmap+0xc2/0x140
  [  259.528100]   iommu_dma_unmap_phys+0x55/0xc0
  [  259.532863]   dma_unmap_phys+0x274/0x2e0
  [  259.537238]   dma_unmap_page_attrs+0x17/0x30
  [  259.542000]   nvme_unmap_data+0x13e/0x280
  [  259.546473]   nvme_pci_complete_batch+0x45/0x70
  [  259.551524]   nvme_irq+0x83/0x90
  [  259.555123]   __handle_irq_event_percpu+0x92/0x360
  [  259.560466]   handle_irq_event+0x39/0x80
  [  259.564841]   handle_edge_irq+0xb2/0x1a0
  [  259.569214]   __common_interrupt+0x4e/0x130
  [  259.573882]   common_interrupt+0x88/0xa0
  [  259.578256]   asm_common_interrupt+0x27/0x40
  [  259.583019]   cpuidle_enter_state+0x119/0x5d0
  [  259.587877]   cpuidle_enter+0x2e/0x50
  [  259.591962]   do_idle+0x153/0x2c0
  [  259.595657]   cpu_startup_entry+0x29/0x30
  [  259.600128]   start_secondary+0x118/0x150
  [  259.604601]   common_startup_64+0x13e/0x141
  [  259.609266]
                 to a HARDIRQ-irq-unsafe lock:
  [  259.615384]  (&xa->xa_lock#25){+.+.}-{3:3}
  [  259.615386]
                 ... which became HARDIRQ-irq-unsafe at:
  [  259.627039] ...
  [  259.627039]   lock_acquire+0xb6/0x2e0
  [  259.633071]   _raw_spin_lock+0x2f/0x50
  [  259.637250]   amd_iommu_alloc_domain_nested+0x140/0x3c0
  [  259.643078]   iommufd_hwpt_alloc+0x272/0x800 [iommufd]
  [  259.648813]   iommufd_fops_ioctl+0x14e/0x200 [iommufd]
  [  259.654547]   __x64_sys_ioctl+0x9d/0xf0
  ...

Since amd_iommu_domain_flush_pages() necessarily holds domain->lock to do the
flush, switch the allocation side in gdom_info_load_or_alloc_locked() to
HARDIRQ-safe allocation. The IOMMU_DESTROY->free path has the same issue,
so switch that path to HARDIRQ-safe locking as well.

## Which versions are affected by CVE-2026-68347?


## How do I fix CVE-2026-68347?

Apply the vendor's patch.

## Is CVE-2026-68347 being exploited?

There is no known exploitation of CVE-2026-68347 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-68347 and fix it if it is affected.

What it is: CVE-2026-68347 is a vulnerability in Linux, published on 10 Aug 2026. 
Exploitation: There is no known exploitation of CVE-2026-68347 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-2026-68347/ (Markdown: https://insights.sbomify.com/CVE-2026-68347/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-68347
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-68347
- OSV: https://osv.dev/vulnerability/CVE-2026-68347

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-68347/
Summaries are generated and may contain mistakes; the official description above is the record.