CVE-2026-80878 in Linux
Summary
by MITRE • 09/04/2026
In the Linux kernel, the following vulnerability has been resolved:
afs: Fix leak of ungot volume
Fix afs_lookup_volume_rcu() so that it doesn't leak a dying volume if afs_try_get_volume() fails.
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Analysis
by VulDB Data Team • 09/04/2026
The identified issue resides within the AFS (Andrew File System) client implementation in the Linux kernel, specifically affecting the function afs_lookup_volume_rcu which is responsible for locating and referencing volume structures during file system operations. This vulnerability manifests as a resource leak where a dying volume object fails to be properly released when the attempt to acquire an additional reference via afs_try_get_volume returns failure. In the context of AFS architecture, volumes are critical data structures that represent logical units of stored data accessible by clients. The RCU (Read-Copy-Update) mechanism is employed to manage concurrent access safely without heavy locking overhead, but it requires strict adherence to reference counting protocols to ensure memory safety and prevent leaks.
The technical flaw arises from an imbalance in the reference counting logic during error handling paths. When afs_lookup_volume_rcu attempts to increment the reference count of a volume using afs_try_get_volume, this function may fail if the volume is already in the process of being destroyed or if certain internal state conditions are not met for acquiring a new reference. In such failure scenarios, the code path previously neglected to release the initial reference that was held prior to the attempt. Consequently, the kernel retains a pointer to a volume object that is marked as dying but never fully deallocated because its final reference count does reach zero. This results in a memory leak where each occurrence consumes kernel heap space without releasing it back to the system pool.
From an operational perspective, this vulnerability poses risks related to resource exhaustion and potential denial of service conditions over extended periods or under high load. Although individual leaks may appear negligible, repeated occurrences during intensive file access patterns can gradually deplete available kernel memory resources. This degradation in system stability can lead to increased latency for other processes relying on the same memory allocator, potentially causing broader performance issues across the operating environment. In extreme cases, persistent leakage could contribute to out-of-memory conditions that trigger aggressive page reclaim or even system crashes if critical subsystems are starved of necessary allocations.
This type of defect aligns with CWE-401, which describes a missing release of memory after effective usage, and falls under the broader category of improper resource management often seen in complex kernel drivers. The failure to handle error conditions correctly within reference-counted data structures is a common source of stability issues in operating system kernels. Mitigation strategies primarily involve applying the upstream Linux kernel patch that corrects the logic flow within afs_lookup_volume_rcu to ensure proper cleanup upon failed acquisition attempts. System administrators should prioritize updating their systems with patched kernel versions as soon as they become available through official distribution channels. Additionally, monitoring tools that track memory allocation patterns in kernel space can help detect early signs of such leaks before they escalate into significant operational disruptions.