# CVE-2025-22031: PCI/bwctrl: Fix NULL pointer dereference on bus number exhaustion

> A NULL pointer dereference in the Linux kernel PCI bandwidth controller can cause a system crash when bus numbers are exhausted.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/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:** 16 Apr 2025
- **Updated:** 11 May 2026
- **Also known as:** BELL-CVE-2025-22031, GHSA-2788-7prj-r2qv, ROOT-OS-DEBIAN-13-CVE-2025-22031, UBUNTU-CVE-2025-22031

## What is CVE-2025-22031?

CVE-2025-22031 is a medium-severity vulnerability in Linux kernel, published on 16 Apr 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:

PCI/bwctrl: Fix NULL pointer dereference on bus number exhaustion

When BIOS neglects to assign bus numbers to PCI bridges, the kernel
attempts to correct that during PCI device enumeration.  If it runs out
of bus numbers, no pci_bus is allocated and the "subordinate" pointer in
the bridge's pci_dev remains NULL.

The PCIe bandwidth controller erroneously does not check for a NULL
subordinate pointer and dereferences it on probe.

Bandwidth control of unusable devices below the bridge is of questionable
utility, so simply error out instead.  This mirrors what PCIe hotplug does
since commit 62e4492c3063 ("PCI: Prevent NULL dereference during pciehp
probe").

The PCI core emits a message with KERN_INFO severity if it has run out of
bus numbers.  PCIe hotplug emits an additional message with KERN_ERR
severity to inform the user that hotplug functionality is disabled at the
bridge.  A similar message for bandwidth control does not seem merited,
given that its only purpose so far is to expose an up-to-date link speed
in sysfs and throttle the link speed on certain laptops with limited
Thermal Design Power.  So error out silently.

User-visible messages:

  pci 0000:16:02.0: bridge configuration invalid ([bus 00-00]), reconfiguring
  [...]
  pci_bus 0000:45: busn_res: [bus 45-74] end is updated to 74
  pci 0000:16:02.0: devices behind bridge are unusable because [bus 45-74] cannot be assigned for them
  [...]
  pcieport 0000:16:02.0: pciehp: Hotplug bridge without secondary bus, ignoring
  [...]
  BUG: kernel NULL pointer dereference
  RIP: pcie_update_link_speed
  pcie_bwnotif_enable
  pcie_bwnotif_probe
  pcie_port_probe_service
  really_probe

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2025-22031?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2025-22031?

Apply the vendor's patch.

## Is CVE-2025-22031 being exploited?

There is no known exploitation of CVE-2025-22031 in the wild and no public exploit code.

## Other vulnerabilities in Linux kernel

- [CVE-2026-53266](https://insights.sbomify.com/CVE-2026-53266/): Linux Kernel Out-of-Bounds Write (high 8.8, exploited in the wild)
- [CVE-2013-6282](https://insights.sbomify.com/CVE-2013-6282/): Linux Kernel Improper Input Validation (high 8.8, exploited in the wild)
- [CVE-2022-0185](https://insights.sbomify.com/CVE-2022-0185/): Linux Kernel Heap-Based Buffer Overflow (high 8.4, exploited in the wild)
- [CVE-2013-2094](https://insights.sbomify.com/CVE-2013-2094/): Linux Kernel Privilege Escalation (high 8.4, exploited in the wild)
- [CVE-2026-53362](https://insights.sbomify.com/CVE-2026-53362/): Linux Kernel Unspecified (high 7.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2025-22031 and fix it if it is affected.

What it is: CVE-2025-22031 is a medium-severity vulnerability in Linux kernel, published on 16 Apr 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-2025-22031 in the wild and no public exploit code.

Affected product: Linux kernel. 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-2025-22031/ (Markdown: https://insights.sbomify.com/CVE-2025-22031/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2025-22031
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2025-22031
- OSV: https://osv.dev/vulnerability/CVE-2025-22031

---
From sbomify Insights: https://insights.sbomify.com/CVE-2025-22031/
Summaries are generated and may contain mistakes; the official description above is the record.