CVE-2024-53143: fsnotify: Fix ordering of iput() and watched_objects decrement

Severity: high (CVSS 7.8 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.2% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2024-12-07 · updated 2026-06-17
Weakness: CWE-416

Description

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.

Affected products

Linux kernel: from 6.10 before 6.11.11; from 6.12 before 6.12.2 — fixed in 6.11.11, 6.12.2

How to fix

Upgrade to a fixed version: Linux kernel 6.11.11, 6.12.2. Check the vendor advisory for mitigations.

References

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