# CVE-2024-26802: stmmac: Clear variable when destroying workqueue

> A null pointer dereference in the stmmac network driver can cause a kernel panic during adapter reset, leading to denial of service.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/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:** 4 Apr 2024
- **Updated:** 5 Aug 2026
- **Also known as:** BELL-CVE-2024-26802, DEBIAN-CVE-2024-26802, GHSA-r7p6-cff4-g6q4, UBUNTU-CVE-2024-26802

## What is CVE-2024-26802?

CVE-2024-26802 is a high-severity vulnerability in Linux kernel, published on 4 Apr 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:

stmmac: Clear variable when destroying workqueue

Currently when suspending driver and stopping workqueue it is checked whether
workqueue is not NULL and if so, it is destroyed.
Function destroy_workqueue() does drain queue and does clear variable, but
it does not set workqueue variable to NULL. This can cause kernel/module
panic if code attempts to clear workqueue that was not initialized.

This scenario is possible when resuming suspended driver in stmmac_resume(),
because there is no handling for failed stmmac_hw_setup(),
which can fail and return if DMA engine has failed to initialize,
and workqueue is initialized after DMA engine.
Should DMA engine fail to initialize, resume will proceed normally,
but interface won't work and TX queue will eventually timeout,
causing 'Reset adapter' error.
This then does destroy workqueue during reset process.
And since workqueue is initialized after DMA engine and can be skipped,
it will cause kernel/module panic.

To secure against this possible crash, set workqueue variable to NULL when
destroying workqueue.

Log/backtrace from crash goes as follows:
[88.031977]------------[ cut here ]------------
[88.031985]NETDEV WATCHDOG: eth0 (sxgmac): transmit queue 1 timed out
[88.032017]WARNING: CPU: 0 PID: 0 at net/sched/sch_generic.c:477 dev_watchdog+0x390/0x398
           <Skipping backtrace for watchdog timeout>
[88.032251]---[ end trace e70de432e4d5c2c0 ]---
[88.032282]sxgmac 16d88000.ethernet eth0: Reset adapter.
[88.036359]------------[ cut here ]------------
[88.036519]Call trace:
[88.036523] flush_workqueue+0x3e4/0x430
[88.036528] drain_workqueue+0xc4/0x160
[88.036533] destroy_workqueue+0x40/0x270
[88.036537] stmmac_fpe_stop_wq+0x4c/0x70
[88.036541] stmmac_release+0x278/0x280
[88.036546] __dev_close_many+0xcc/0x158
[88.036551] dev_close_many+0xbc/0x190
[88.036555] dev_close.part.0+0x70/0xc0
[88.036560] dev_close+0x24/0x30
[88.036564] stmmac_service_task+0x110/0x140
[88.036569] process_one_work+0x1d8/0x4a0
[88.036573] worker_thread+0x54/0x408
[88.036578] kthread+0x164/0x170
[88.036583] ret_from_fork+0x10/0x20
[88.036588]---[ end trace e70de432e4d5c2c1 ]---
[88.036597]Unable to handle kernel NULL pointer dereference at virtual address 0000000000000004

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2024-26802?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2024-26802?

Apply the vendor's patch.

## Is CVE-2024-26802 being exploited?

There is no known exploitation of CVE-2024-26802 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-2024-26802 and fix it if it is affected.

What it is: CVE-2024-26802 is a high-severity vulnerability in Linux kernel, published on 4 Apr 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-2024-26802 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-2024-26802/ (Markdown: https://insights.sbomify.com/CVE-2024-26802/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2024-26802
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2024-26802
- OSV: https://osv.dev/vulnerability/CVE-2024-26802

---
From sbomify Insights: https://insights.sbomify.com/CVE-2024-26802/
Summaries are generated and may contain mistakes; the official description above is the record.