# CVE-2021-47523: IB/hfi1: Fix leak of rcvhdrtail_dummy_kvaddr

> A memory leak in the Linux kernel IB/hfi1 driver allows attackers to cause resource exhaustion and denial of service via repeated device reinitialization.

- **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:** 24 May 2024
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2021-47523, UBUNTU-CVE-2021-47523

## What is CVE-2021-47523?

CVE-2021-47523 is a medium-severity vulnerability in Linux kernel, published on 24 May 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:

IB/hfi1: Fix leak of rcvhdrtail_dummy_kvaddr

This buffer is currently allocated in hfi1_init():

	if (reinit)
		ret = init_after_reset(dd);
	else
		ret = loadtime_init(dd);
	if (ret)
		goto done;

	/* allocate dummy tail memory for all receive contexts */
	dd->rcvhdrtail_dummy_kvaddr = dma_alloc_coherent(&dd->pcidev->dev,
							 sizeof(u64),
							 &dd->rcvhdrtail_dummy_dma,
							 GFP_KERNEL);

	if (!dd->rcvhdrtail_dummy_kvaddr) {
		dd_dev_err(dd, "cannot allocate dummy tail memory\n");
		ret = -ENOMEM;
		goto done;
	}

The reinit triggered path will overwrite the old allocation and leak it.

Fix by moving the allocation to hfi1_alloc_devdata() and the deallocation
to hfi1_free_devdata().

Weakness: CWE-401 (Missing Release of Memory after Effective Lifetime)

## Which versions are affected by CVE-2021-47523?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2021-47523?

Apply the vendor's patch.

## Is CVE-2021-47523 being exploited?

There is no known exploitation of CVE-2021-47523 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-2021-47523 and fix it if it is affected.

What it is: CVE-2021-47523 is a medium-severity vulnerability in Linux kernel, published on 24 May 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-2021-47523 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-2021-47523/ (Markdown: https://insights.sbomify.com/CVE-2021-47523/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47523
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47523
- OSV: https://osv.dev/vulnerability/CVE-2021-47523

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-47523/
Summaries are generated and may contain mistakes; the official description above is the record.