---
id: "CVE-2026-99158"
kind: "vulnerability"
aliases: ["CVE-2026-99158"]
title: "Linux kernel: false warning in ring buffer mmap reader under load"
severity: "unknown"
cvss: null
epss: null
exploited: false
status: "open"
category: "runtime"
products: []
ecosystems: []
tags: ["kernel", "linux", "runtime", "tracing"]
not_affected_if: []
published_at: "2026-10-28T11:17:36+00:00"
first_seen_at: "2026-10-28T11:32:36+00:00"
updated_at: "2026-10-28T11:35:47+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-99158", "first_seen_at": "2026-10-28T11:32:36+00:00"}]
---

# Linux kernel: false warning in ring buffer mmap reader under load

The Linux kernel's ring buffer mmap reader could emit a spurious kernel warning when it caught up with a writer still committing events. The fix treats that case as a normal no-data exit, so the warning no longer fires.

_Summary, check and fix written by a model from the sources; labelled as such._

## Timeline

- 2026-10-28T11:32:36+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-99158

## From the sources

In the Linux kernel, the following vulnerability has been resolved:

ring-buffer: Fix false warning in ring_buffer_map_get_reader()

The mmap reader can warn when it catches up with a writer that is still
committing events. rb_get_reader_page() returns NULL in this case, but
ring_buffer_map_get_reader() treats that result as an error.

The initial rb_per_cpu_empty() check filters out an empty buffer, but it
does not guarantee that the next reader page has committed data. Writers
do not take reader_lock and can advance commit_page before publishing the
committed length on the new page. rb_get_reader_page() can swap to that
page, catch up with the writer and return NULL.

Handle NULL through the existing no-data exit without warning. Remove the
caller's reader_page == commit_page check as well, since the reader-page
helper already handles that case. The existing metadata update and return
path remain in place.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_