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.

Severity MEDIUM

CVSS Score 4.7

CVSS Vector CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H

CWE CWE-362

Public Exploit ✅ No

Source NVD

Published 2024-10-09

Updated 2026-06-02

Modified 2026-05-12

Fix URL https://git.kernel.org/stable/c/172e422ffea20a89bfdc672741c1aad6fbb5044e

Software	From version	Fixed in
linux-kernel	6.7	6.10.9