# CVE-2024-56641: net/smc: initialize close_work early to avoid warning

> A race condition in the Linux kernel SMC module can cause a null pointer dereference warning and potential system instability during connection termination.

- **Severity:** High 7.5 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 27 Dec 2024
- **Updated:** 15 Oct 2026
- **Also known as:** AZL-68220, BELL-CVE-2024-56641, DEBIAN-CVE-2024-56641, GHSA-mv4p-vmf8-27c9, ROOT-OS-DEBIAN-11-CVE-2024-56641, ROOT-OS-DEBIAN-12-CVE-2024-56641, ROOT-OS-UBUNTU-2204-CVE-2024-56641, UBUNTU-CVE-2024-56641

## What is CVE-2024-56641?

CVE-2024-56641 is a high-severity vulnerability in Linux kernel, published on 27 Dec 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

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

net/smc: initialize close_work early to avoid warning

We encountered a warning that close_work was canceled before
initialization.

  WARNING: CPU: 7 PID: 111103 at kernel/workqueue.c:3047 __flush_work+0x19e/0x1b0
  Workqueue: events smc_lgr_terminate_work [smc]
  RIP: 0010:__flush_work+0x19e/0x1b0
  Call Trace:
   ? __wake_up_common+0x7a/0x190
   ? work_busy+0x80/0x80
   __cancel_work_timer+0xe3/0x160
   smc_close_cancel_work+0x1a/0x70 [smc]
   smc_close_active_abort+0x207/0x360 [smc]
   __smc_lgr_terminate.part.38+0xc8/0x180 [smc]
   process_one_work+0x19e/0x340
   worker_thread+0x30/0x370
   ? process_one_work+0x340/0x340
   kthread+0x117/0x130
   ? __kthread_cancel_work+0x50/0x50
   ret_from_fork+0x22/0x30

This is because when smc_close_cancel_work is triggered, e.g. the RDMA
driver is rmmod and the LGR is terminated, the conn->close_work is
flushed before initialization, resulting in WARN_ON(!work->func).

__smc_lgr_terminate             | smc_connect_{rdma|ism}
-------------------------------------------------------------
                                | smc_conn_create
				| \- smc_lgr_register_conn
for conn in lgr->conns_all      |
\- smc_conn_kill                |
   \- smc_close_active_abort    |
      \- smc_close_cancel_work  |
         \- cancel_work_sync    |
            \- __flush_work     |
	         (close_work)   |
	                        | smc_close_init
	                        | \- INIT_WORK(&close_work)

So fix this by initializing close_work before establishing the
connection.

## Which versions are affected by CVE-2024-56641?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-56641?

Apply the vendor's patch.

## Is CVE-2024-56641 being exploited?

There is no known exploitation of CVE-2024-56641 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-2024-56641 and fix it if it is affected.

What it is: CVE-2024-56641 is a high-severity vulnerability in Linux kernel, published on 27 Dec 2024. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2024-56641 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-2024-56641/ (Markdown: https://insights.sbomify.com/CVE-2024-56641/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-56641
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-56641
- OSV: https://osv.dev/vulnerability/CVE-2024-56641

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-56641/
Summaries are generated and may contain mistakes; the official description above is the record.