# CVE-2021-47192: scsi: core: sysfs: Fix hang when device state is set via sysfs

> A race condition in the Linux kernel SCSI subsystem can cause a system hang when setting device state via sysfs during iSCSI recovery.

- **Severity:** Medium 5.3 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:N/A:N`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 10 Apr 2024
- **Updated:** 23 May 2026
- **Also known as:** DEBIAN-CVE-2021-47192, GHSA-f834-hvgh-g5v9, UBUNTU-CVE-2021-47192

## What is CVE-2021-47192?

CVE-2021-47192 is a medium-severity vulnerability in Linux kernel, published on 10 Apr 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:

scsi: core: sysfs: Fix hang when device state is set via sysfs

This fixes a regression added with:

commit f0f82e2476f6 ("scsi: core: Fix capacity set to zero after
offlinining device")

The problem is that after iSCSI recovery, iscsid will call into the kernel
to set the dev's state to running, and with that patch we now call
scsi_rescan_device() with the state_mutex held. If the SCSI error handler
thread is just starting to test the device in scsi_send_eh_cmnd() then it's
going to try to grab the state_mutex.

We are then stuck, because when scsi_rescan_device() tries to send its I/O
scsi_queue_rq() calls -> scsi_host_queue_ready() -> scsi_host_in_recovery()
which will return true (the host state is still in recovery) and I/O will
just be requeued. scsi_send_eh_cmnd() will then never be able to grab the
state_mutex to finish error handling.

To prevent the deadlock move the rescan-related code to after we drop the
state_mutex.

This also adds a check for if we are already in the running state. This
prevents extra scans and helps the iscsid case where if the transport class
has already onlined the device during its recovery process then we don't
need userspace to do it again plus possibly block that daemon.

Weakness: CWE-667 (Improper Locking)

## Which versions are affected by CVE-2021-47192?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2021-47192?

Apply the vendor's patch.

## Is CVE-2021-47192 being exploited?

There is no known exploitation of CVE-2021-47192 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-2021-47192 and fix it if it is affected.

What it is: CVE-2021-47192 is a medium-severity vulnerability in Linux kernel, published on 10 Apr 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-2021-47192 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-2021-47192/ (Markdown: https://insights.sbomify.com/CVE-2021-47192/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47192
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47192
- OSV: https://osv.dev/vulnerability/CVE-2021-47192

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-47192/
Summaries are generated and may contain mistakes; the official description above is the record.