CVE-2026-98445 in Linux
Summary
by MITRE • 10/18/2026
In the Linux kernel, the following vulnerability has been resolved:
xfs: don't let memory failures leak blocks and kill repairs
LOLLM complains that a memory allocation failure in xrep_newbt_add_blocks results in online repair leaking blocks that were previously allocated to write a new btree, but the problem is worse than that -- a limitation of the codebase is that the callers cannot undo the transaction /and/ return the error -- either you undo all changes and commit the transaction, or you error out and the filesystem goes down.
However, the new btree space reservation object isn't that big (~48 bytes). Let's just do a NOFAIL allocation and the problem goes away.
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Analysis
by VulDB Data Team • 10/19/2026
The Linux kernel’s XFS file system contains a vulnerability related to memory allocation failures during online repair operations, specifically within the xrep_newbt_add_blocks function. This issue stems from an inability of the codebase to gracefully handle out-of-memory conditions without compromising filesystem integrity or requiring a full transaction rollback that forces an unmount. When a memory allocation fails in this context, previously allocated blocks intended for writing a new btree are leaked rather than being properly released back to the free space management system. This leakage represents a resource exhaustion vector that can degrade performance over time and potentially lead to filesystem corruption if left unchecked across multiple repair cycles or heavy workloads.
The root cause lies in architectural limitations within the XFS transaction handling mechanism for online repairs. The existing logic dictates that callers cannot simultaneously undo specific changes and return an error code without triggering a catastrophic failure mode where the entire filesystem must be taken offline. This binary choice between committing all changes or aborting entirely creates a dangerous gap when memory allocation fails mid-operation. If the system attempts to roll back, it may leave inconsistent states; if it proceeds despite the failure, allocated blocks are orphaned and lost from the perspective of space reclamation algorithms.
To mitigate this risk, developers have implemented a fix that utilizes NOFAIL allocations for the new btree space reservation object. Given that the size requirement is minimal at approximately forty-eight bytes, enforcing non-failing memory allocation ensures that critical repair operations can complete successfully even under high memory pressure. This approach eliminates the possibility of block leakage caused by transient allocation failures and prevents unnecessary filesystem unmounts during online repairs. By prioritizing reliability for such small but essential allocations, the stability of XFS file systems is significantly improved without introducing significant overhead or performance penalties.
From a security perspective, this vulnerability aligns with CWE-401 which describes missing release of memory after successful allocation leading to resource exhaustion. Although not directly exploitable by an external attacker in most scenarios due to its reliance on internal repair mechanisms and specific workload conditions, it poses a risk for denial-of-service through gradual degradation or forced unmounts that disrupt service availability. The ATT&CK framework categorizes such issues under T1496 Resource Hijacking as they involve the improper management of system resources which can be leveraged to degrade operational continuity. Administrators should ensure their kernels are updated with this patch applied, particularly in environments where online filesystem repairs are frequently performed or memory pressure is common during maintenance windows. Regular monitoring of XFS health metrics and prompt application of kernel updates remain essential practices for maintaining robust storage infrastructure integrity against such internal logic flaws.