# CVE-2023-54095: powerpc/iommu: Fix notifiers being shared by PCI and VIO buses

> A kernel bug causes memory corruption when PCI and VIO bus notifiers are shared, potentially leading to system crashes.

- **Severity:** High 7.0 (`CVSS:3.1/AV:L/AC:H/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:** 24 Dec 2025
- **Updated:** 15 Oct 2026
- **Also known as:** BELL-CVE-2023-54095, DEBIAN-CVE-2023-54095, GHSA-6v42-prqv-7q9g, UBUNTU-CVE-2023-54095

## What is CVE-2023-54095?

CVE-2023-54095 is a high-severity memory corruption vulnerability in Linux, published on 24 Dec 2025. 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:

powerpc/iommu: Fix notifiers being shared by PCI and VIO buses

fail_iommu_setup() registers the fail_iommu_bus_notifier struct to both
PCI and VIO buses.  struct notifier_block is a linked list node, so this
causes any notifiers later registered to either bus type to also be
registered to the other since they share the same node.

This causes issues in (at least) the vgaarb code, which registers a
notifier for PCI buses.  pci_notify() ends up being called on a vio
device, converted with to_pci_dev() even though it's not a PCI device,
and finally makes a bad access in vga_arbiter_add_pci_device() as
discovered with KASAN:

 BUG: KASAN: slab-out-of-bounds in vga_arbiter_add_pci_device+0x60/0xe00
 Read of size 4 at addr c000000264c26fdc by task swapper/0/1

 Call Trace:
   dump_stack_lvl+0x1bc/0x2b8 (unreliable)
   print_report+0x3f4/0xc60
   kasan_report+0x244/0x698
   __asan_load4+0xe8/0x250
   vga_arbiter_add_pci_device+0x60/0xe00
   pci_notify+0x88/0x444
   notifier_call_chain+0x104/0x320
   blocking_notifier_call_chain+0xa0/0x140
   device_add+0xac8/0x1d30
   device_register+0x58/0x80
   vio_register_device_node+0x9ac/0xce0
   vio_bus_scan_register_devices+0xc4/0x13c
   __machine_initcall_pseries_vio_device_init+0x94/0xf0
   do_one_initcall+0x12c/0xaa8
   kernel_init_freeable+0xa48/0xba8
   kernel_init+0x64/0x400
   ret_from_kernel_thread+0x5c/0x64

Fix this by creating separate notifier_block structs for each bus type.

[mpe: Add #ifdef to fix CONFIG_IBMVIO=n build]

## Which versions are affected by CVE-2023-54095?


## How do I fix CVE-2023-54095?

Apply the vendor's patch.

## Is CVE-2023-54095 being exploited?

There is no known exploitation of CVE-2023-54095 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2023-54095 and fix it if it is affected.

What it is: CVE-2023-54095 is a high-severity memory corruption vulnerability in Linux, published on 24 Dec 2025. 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-2023-54095 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-2023-54095/ (Markdown: https://insights.sbomify.com/CVE-2023-54095/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2023-54095
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2023-54095
- OSV: https://osv.dev/vulnerability/CVE-2023-54095

---
From sbomify Insights: https://insights.sbomify.com/CVE-2023-54095/
Summaries are generated and may contain mistakes; the official description above is the record.