Linux Kernel ext4 Orphan Inode Cleanup Hang Vulnerability

A vulnerability in the Linux kernel's ext4 file system can lead to a hung task issue. This problem arises during the cleanup of orphan inodes, where an extended attribute (EA) inode is found to be in the process of being deleted. The reference counting mechanism causes the system to wait indefinitely for the deletion to complete, leading to a task being blocked for an extended period. The issue has been observed in Linux kernel version 6.2.0-rc2.

Impact

The vulnerability causes a task to be blocked for an extended period, leading to a hung task situation where the task cannot proceed because it is waiting for a resource that is not available.

Reproduction

The vulnerability can be reproduced by triggering the orphan inode cleanup process in the ext4 file system. This can be done by creating a scenario where an inode is marked as orphaned and then has an extended attribute entry that references it. During the cleanup process, the reference counting mechanism will cause the task to wait indefinitely, blocking it for more than 143 seconds.

Remediation

Users can upgrade to the latest stable version of the Linux kernel where this vulnerability has been addressed.