CVE-2024-47660

Technical 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.

Remediation

Check the references section for vendor advisories and patches from linux. Update linux_kernel to the latest patched version. If immediate patching is not possible, review the CVSS vector to understand the attack surface and apply compensating controls such as network segmentation or access restrictions.

Affected Products

References