Linux Kernel up to 6.11.10/6.12.1 fsnotify iput use after free

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.11.10/6.12.1. It has been rated as problematic. The impacted element is the function iput of the component fsnotify. Performing a manipulation results in an unknown weakness. This vulnerability is reported as CVE-2024-53143. No exploit exists. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as problematic has been found in Linux Kernel up to 6.11.10/6.12.1. This affects the function iput of the component fsnotify. CWE is classifying the issue as CWE-416. Referencing memory after it has been freed can cause a program to crash, use unexpected values, or execute code. The impact remains unknown. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: fsnotify: Fix ordering of iput() and watched_objects decrement Ensure the superblock is kept alive until we're done with iput(). Holding a reference to an inode is not allowed unless we ensure the superblock stays alive, which fsnotify does by keeping the watched_objects count elevated, so iput() must happen before the watched_objects decrement. This can lead to a UAF of something like sb->s_fs_info in tmpfs, but the UAF is hard to hit because race orderings that oops are more likely, thanks to the CHECK_DATA_CORRUPTION() block in generic_shutdown_super(). Also, ensure that fsnotify_put_sb_watched_objects() doesn't call fsnotify_sb_watched_objects() on a superblock that may have already been freed, which would cause a UAF read of sb->s_fsnotify_info.

The advisory is shared at git.kernel.org. This vulnerability is uniquely identified as CVE-2024-53143 since 11/19/2024. The exploitability is told to be difficult. Technical details are known, but no exploit is available. The price for an exploit might be around USD $0-$5k at the moment (estimation calculated on 02/20/2025).

The vulnerability scanner Nessus provides a plugin with the ID 216493 (Ubuntu 24.10 : Linux kernel vulnerabilities (USN-7276-1)), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.11.11 or 6.12.2 eliminates this vulnerability. Applying the patch 45a8f8232a49/83af1cfa10d9/21d1b618b6b9 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 vulnerability database at Tenable (216493). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.11.0
• 6.11.1
• 6.11.2
• 6.11.3
• 6.11.4
• 6.11.5
• 6.11.6
• 6.11.7
• 6.11.8
• 6.11.9
• 6.11.10
• 6.12.0
• 6.12.1

License

• open-source

Website

• Vendor: https://www.kernel.org/

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Entryinfo

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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