CVE-2026-98448 in Linux
Summary
by MITRE • 10/18/2026
In the Linux kernel, the following vulnerability has been resolved:
xfs: release orphanage dir inode if chown fails
LOLLM points out that we leak the igrab'd reference to the orphanage directory inode if chowning it fails. Fix that.
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Analysis
by VulDB Data Team • 10/18/2026
The Linux kernel's XFS filesystem implementation contained a resource management flaw within its handling of file ownership changes, specifically when operating on inodes associated with the orphanage directory structure. The vulnerability arises during the execution of change owner operations where the system attempts to modify the user or group identifiers for files that are currently being processed through the orphan cleanup mechanism. In this specific code path, the kernel acquires a reference count increment on the inode representing the orphanage directory by invoking the igrab function. This operation is standard practice in VFS layer interactions to ensure the target object remains valid and accessible throughout the duration of the transaction, preventing premature deallocation while operations are pending.
The critical technical flaw occurs when the subsequent chown system call encounters an error condition that prevents it from completing successfully. Under normal circumstances, if a file operation fails after acquiring references, the kernel is responsible for releasing those references to maintain memory integrity and prevent resource exhaustion. However, in this specific instance, the code path lacked the necessary cleanup logic to decrement the reference count obtained via igrab when the chown operation returned an error. Consequently, the inode reference was not released back to the system pool, resulting in a persistent leak of kernel memory resources associated with that inode structure.
This type of vulnerability is classified under CWE-401, which describes missing release of memory after effective lifetime, and more specifically relates to improper resource management leading to resource leaks. From an operational perspective, while a single instance might seem negligible, the cumulative effect of repeated failed chown operations on orphaned files can lead to significant kernel memory consumption over time. In severe cases, such as those highlighted by Long Term Linux Memory Leak (LOLLM) analysis techniques, these small leaks can contribute to broader system instability or denial-of-service conditions if they exhaust available kernel slab cache resources. The impact is primarily localized to the node running the affected XFS filesystem and requires repeated triggering events to manifest noticeable degradation in system performance or stability.
To mitigate this vulnerability, users must apply the specific patch provided by the Linux distribution maintainers that addresses the reference counting logic within the xfs_chown_file function. This fix ensures that if the chown operation fails after acquiring the orphanage directory inode reference, the code correctly invokes iput to release the reference and decrement the count appropriately. Administrators should verify their kernel versions against vendor advisories and apply security updates promptly. Additionally, monitoring for unusual growth in slab cache usage or specific XFS-related memory metrics can help identify systems that may have been subjected to repeated exploitation attempts of this flaw before patches were applied.