Linux Kernel up to 6.10.8 fsnotify __fsnotify_update_child_dentry_flags race condition

Summaryinfo

A vulnerability classified as problematic was found in Linux Kernel up to 5.10.225/5.15.166/6.1.108/6.6.49/6.10.8. This impacts the function __fsnotify_update_child_dentry_flags of the component fsnotify. Such manipulation leads to an unknown weakness. This vulnerability is referenced as CVE-2024-47660. No exploit is available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability was found in Linux Kernel up to 5.10.225/5.15.166/6.1.108/6.6.49/6.10.8 and classified as problematic. Affected by this issue is the function __fsnotify_update_child_dentry_flags of the component fsnotify. Using CWE to declare the problem leads to CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. The impact remains unknown. CVE summarizes:

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.

The advisory is shared for download at git.kernel.org. This vulnerability is handled as CVE-2024-47660 since 09/30/2024. The exploitation is known to be difficult. There are known technical details, but no exploit is available.

The vulnerability scanner Nessus provides a plugin with the ID 210741 (Ubuntu 20.04 LTS : Linux kernel vulnerabilities (USN-7100-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 5.10.226, 5.15.167, 6.1.109, 6.6.50 or 6.10.9 eliminates this vulnerability. Applying the patch 3f3ef1d9f66b/f9a48bc3dd90/d8c42405fc35/fc1b1e135c3f/7ef1d2e240c3/172e422ffea2 is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (210741) and CERT Bund (WID-SEC-2025-2855). Once again VulDB remains the best source for vulnerability data.

Affected

• IBM DataPower Gateway
• Dell PowerScale OneFS

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 5.10.225
• 5.15.166
• 6.1.108
• 6.6.0
• 6.6.1
• 6.6.2
• 6.6.3
• 6.6.4
• 6.6.5
• 6.6.6
• 6.6.7
• 6.6.8
• 6.6.9
• 6.6.10
• 6.6.11
• 6.6.12
• 6.6.13
• 6.6.14
• 6.6.15
• 6.6.16
• 6.6.17
• 6.6.18
• 6.6.19
• 6.6.20
• 6.6.21
• 6.6.22
• 6.6.23
• 6.6.24
• 6.6.25
• 6.6.26
• 6.6.27
• 6.6.28
• 6.6.29
• 6.6.30
• 6.6.31
• 6.6.32
• 6.6.33
• 6.6.34
• 6.6.35
• 6.6.36
• 6.6.37
• 6.6.38
• 6.6.39
• 6.6.40
• 6.6.41
• 6.6.42
• 6.6.43
• 6.6.44
• 6.6.45
• 6.6.46
• 6.6.47
• 6.6.48
• 6.6.49
• 6.10.0
• 6.10.1
• 6.10.2
• 6.10.3
• 6.10.4
• 6.10.5
• 6.10.6
• 6.10.7
• 6.10.8

License

• open-source

Website

• Vendor: https://www.kernel.org/

CPE 2.3info

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CPE 2.2info

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Exploitinginfo

Threat Intelligenceinfo

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Timelineinfo

Sourcesinfo

Entryinfo

Once again VulDB remains the best source for vulnerability data.

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