# CVE-2021-47187: arm64: dts: qcom: msm8998: Fix CPU/L2 idle state latency and residency

> Incorrect idle state timings in the Linux kernel for MSM8998 devices cause random reboots and lockups when CPU scaling is enabled.

- **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:** 10 Apr 2024
- **Updated:** 11 May 2026
- **Also known as:** DEBIAN-CVE-2021-47187, GHSA-28cr-jmcx-rqcp, UBUNTU-CVE-2021-47187

## What is CVE-2021-47187?

CVE-2021-47187 is a medium-severity denial of service vulnerability in Linux kernel, published on 10 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:

arm64: dts: qcom: msm8998: Fix CPU/L2 idle state latency and residency

The entry/exit latency and minimum residency in state for the idle
states of MSM8998 were ..bad: first of all, for all of them the
timings were written for CPU sleep but the min-residency-us param
was miscalculated (supposedly, while porting this from downstream);
Then, the power collapse states are setting PC on both the CPU
cluster *and* the L2 cache, which have different timings: in the
specific case of L2 the times are higher so these ones should be
taken into account instead of the CPU ones.

This parameter misconfiguration was not giving particular issues
because on MSM8998 there was no CPU scaling at all, so cluster/L2
power collapse was rarely (if ever) hit.
When CPU scaling is enabled, though, the wrong timings will produce
SoC unstability shown to the user as random, apparently error-less,
sudden reboots and/or lockups.

This set of parameters are stabilizing the SoC when CPU scaling is
ON and when power collapse is frequently hit.

## Which versions are affected by CVE-2021-47187?

It affects 1 product.


Products: Linux kernel.

## How do I fix CVE-2021-47187?

Apply the vendor's patch.

## Is CVE-2021-47187 being exploited?

There is no known exploitation of CVE-2021-47187 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-2021-47187 and fix it if it is affected.

What it is: CVE-2021-47187 is a medium-severity denial of service vulnerability in Linux kernel, published on 10 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-2021-47187 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-2021-47187/ (Markdown: https://insights.sbomify.com/CVE-2021-47187/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-47187
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-47187
- OSV: https://osv.dev/vulnerability/CVE-2021-47187

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-47187/
Summaries are generated and may contain mistakes; the official description above is the record.