# CVE-2024-56649: net: enetc: Do not configure preemptible TCs if SIs do not support

> A null pointer dereference in the ENETC network driver allows local attackers to crash the system by configuring MQPRIO on unsupported interfaces.

- **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:** 27 Dec 2024
- **Updated:** 11 May 2026
- **Also known as:** AZL-54848, BELL-CVE-2024-56649, DEBIAN-CVE-2024-56649, GHSA-h3qm-53p9-w8c6, UBUNTU-CVE-2024-56649

## What is CVE-2024-56649?

CVE-2024-56649 is a medium-severity vulnerability in Linux kernel, published on 27 Dec 2024. 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:

net: enetc: Do not configure preemptible TCs if SIs do not support

Both ENETC PF and VF drivers share enetc_setup_tc_mqprio() to configure
MQPRIO. And enetc_setup_tc_mqprio() calls enetc_change_preemptible_tcs()
to configure preemptible TCs. However, only PF is able to configure
preemptible TCs. Because only PF has related registers, while VF does not
have these registers. So for VF, its hw->port pointer is NULL. Therefore,
VF will access an invalid pointer when accessing a non-existent register,
which will cause a crash issue. The simplified log is as follows.

root@ls1028ardb:~# tc qdisc add dev eno0vf0 parent root handle 100: \
mqprio num_tc 4 map 0 0 1 1 2 2 3 3 queues 1@0 1@1 1@2 1@3 hw 1
[  187.290775] Unable to handle kernel paging request at virtual address 0000000000001f00
[  187.424831] pc : enetc_mm_commit_preemptible_tcs+0x1c4/0x400
[  187.430518] lr : enetc_mm_commit_preemptible_tcs+0x30c/0x400
[  187.511140] Call trace:
[  187.513588]  enetc_mm_commit_preemptible_tcs+0x1c4/0x400
[  187.518918]  enetc_setup_tc_mqprio+0x180/0x214
[  187.523374]  enetc_vf_setup_tc+0x1c/0x30
[  187.527306]  mqprio_enable_offload+0x144/0x178
[  187.531766]  mqprio_init+0x3ec/0x668
[  187.535351]  qdisc_create+0x15c/0x488
[  187.539023]  tc_modify_qdisc+0x398/0x73c
[  187.542958]  rtnetlink_rcv_msg+0x128/0x378
[  187.547064]  netlink_rcv_skb+0x60/0x130
[  187.550910]  rtnetlink_rcv+0x18/0x24
[  187.554492]  netlink_unicast+0x300/0x36c
[  187.558425]  netlink_sendmsg+0x1a8/0x420
[  187.606759] ---[ end trace 0000000000000000 ]---

In addition, some PFs also do not support configuring preemptible TCs,
such as eno1 and eno3 on LS1028A. It won't crash like it does for VFs,
but we should prevent these PFs from accessing these unimplemented
registers.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2024-56649?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-56649?

Apply the vendor's patch.

## Is CVE-2024-56649 being exploited?

There is no known exploitation of CVE-2024-56649 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-2024-56649 and fix it if it is affected.

What it is: CVE-2024-56649 is a medium-severity vulnerability in Linux kernel, published on 27 Dec 2024. 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-2024-56649 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-2024-56649/ (Markdown: https://insights.sbomify.com/CVE-2024-56649/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-56649
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-56649
- OSV: https://osv.dev/vulnerability/CVE-2024-56649

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-56649/
Summaries are generated and may contain mistakes; the official description above is the record.