# CVE-2021-47554: vdpa_sim: avoid putting an uninitialized iova_domain

> A null pointer dereference in the Linux kernel's vdpa_sim module can cause a system crash when an error occurs during device creation.

- **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-2021-47554, UBUNTU-CVE-2021-47554

## What is CVE-2021-47554?

CVE-2021-47554 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:

vdpa_sim: avoid putting an uninitialized iova_domain

The system will crash if we put an uninitialized iova_domain, this
could happen when an error occurs before initializing the iova_domain
in vdpasim_create().

BUG: kernel NULL pointer dereference, address: 0000000000000000
...
RIP: 0010:__cpuhp_state_remove_instance+0x96/0x1c0
...
Call Trace:
 <TASK>
 put_iova_domain+0x29/0x220
 vdpasim_free+0xd1/0x120 [vdpa_sim]
 vdpa_release_dev+0x21/0x40 [vdpa]
 device_release+0x33/0x90
 kobject_release+0x63/0x160
 vdpasim_create+0x127/0x2a0 [vdpa_sim]
 vdpasim_net_dev_add+0x7d/0xfe [vdpa_sim_net]
 vdpa_nl_cmd_dev_add_set_doit+0xe1/0x1a0 [vdpa]
 genl_family_rcv_msg_doit+0x112/0x140
 genl_rcv_msg+0xdf/0x1d0
 ...

So we must make sure the iova_domain is already initialized before
put it.

In addition, we may get the following warning in this case:
WARNING: ... drivers/iommu/iova.c:344 iova_cache_put+0x58/0x70

So we must make sure the iova_cache_put() is invoked only if the
iova_cache_get() is already invoked. Let's fix it together.

Weakness: CWE-908 (Use of Uninitialized Resource)

## Which versions are affected by CVE-2021-47554?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2021-47554?

Apply the vendor's patch.

## Is CVE-2021-47554 being exploited?

There is no known exploitation of CVE-2021-47554 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-2021-47554 and fix it if it is affected.

What it is: CVE-2021-47554 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-2021-47554 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-2021-47554/ (Markdown: https://insights.sbomify.com/CVE-2021-47554/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47554
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47554
- OSV: https://osv.dev/vulnerability/CVE-2021-47554

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-47554/
Summaries are generated and may contain mistakes; the official description above is the record.