CVE-2026-72189 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
ntfs: fail attrlist updates when the superblock is inactive
generic_shutdown_super() clears SB_ACTIVE before evicting cached inodes. If eviction selects the fake inode for a base inode's unnamed $ATTRIBUTE_LIST attribute, ntfs_evict_big_inode() drops the fake inode's reference on the base inode while the fake inode is still hashed and marked I_FREEING.
That iput can synchronously write back the base inode. The writeback path may update mapping pairs and call ntfs_attrlist_update(), which unconditionally calls ntfs_attr_iget() for the same $ATTRIBUTE_LIST fake inode. VFS then finds the I_FREEING inode and waits for eviction to finish, but the current task is still inside that eviction path, causing a self-deadlock in find_inode().
Fix this by mirroring the teardown guard used by __ntfs_write_inode(): once SB_ACTIVE has been cleared, do not try to iget the attribute-list fake inode. Return -EIO so teardown aborts the update instead of waiting on the inode it is evicting.
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Analysis
by VulDB Data Team • 08/15/2026
This vulnerability exists within the ntfs filesystem driver of the linux kernel and represents a critical self-deadlock condition that can lead to system hangs and potential denial of service scenarios. The flaw occurs during the shutdown process when the generic_shutdown_super() function clears the SB_ACTIVE flag on the superblock before proceeding with eviction of cached inodes. This sequence creates a race condition where the eviction process may select the fake inode associated with a base inode's unnamed $ATTRIBUTE_LIST attribute, leading to a complex interaction between inode management and filesystem teardown operations.
The technical root cause stems from the specific ordering of operations during filesystem shutdown where ntfs_evict_big_inode() drops the reference on the base inode while the fake inode remains hashed and marked with I_FREEING flag. When the iput function synchronously writes back the base inode during this critical period, the writeback path triggers ntfs_attrlist_update() which unconditionally calls ntfs_attr_iget() for the same $ATTRIBUTE_LIST fake inode that is already in the process of being evicted. This creates a circular dependency where the VFS layer attempts to find the I_FREEING inode and waits for its eviction to complete, while the current task remains trapped within the eviction path itself.
This vulnerability directly maps to CWE-367 weakness category related to Time-of-Check to Time-of-Use (TOCTOU) race conditions and potentially aligns with ATT&CK technique T1490 for Data Destruction through system resource exhaustion or process lockups. The self-deadlock condition prevents the filesystem shutdown from completing properly, which can result in kernel hangs, system instability, and potential crashes when multiple processes are attempting to access the affected ntfs filesystem during shutdown operations.
The fix implements a teardown guard mechanism similar to that used by __ntfs_write_inode() function, where once SB_ACTIVE has been cleared by generic_shutdown_super(), the system should not attempt to iget the attribute-list fake inode. Instead, the function returns -EIO which causes the teardown process to abort the update operation rather than entering an infinite wait state on the inode it is attempting to evict. This approach prevents the circular dependency while maintaining proper error handling and graceful shutdown behavior for ntfs filesystems.
This remediation addresses a fundamental flaw in the kernel's inode management during filesystem teardown operations and demonstrates the importance of careful synchronization between filesystem shutdown procedures and inode eviction processes. The solution ensures that the system can properly handle cleanup operations without creating deadlock conditions, thereby maintaining system stability and preventing denial of service scenarios that could occur when ntfs filesystems are mounted and subsequently unmounted during system operations or shutdown sequences.