CVE-2026-93261
Received Received - Intake

NULL Pointer Dereference in Linux Kernel Locking Subsystem

Publication date: 2026-09-24

Last updated on: 2026-09-24

Assigner: kernel.org

Description
In the Linux kernel, the following vulnerability has been resolved: locking/lockdep: Fix NULL pointer dereference in __lock_set_class() register_lock_class() can return NULL when the lock class pool is exhausted, graph_lock() fails, or key validation fails. However, __lock_set_class() uses the return value directly in pointer arithmetic without a NULL check: class = register_lock_class(lock, subclass, 0); hlock->class_idx = class - lock_classes; If class is NULL, this computes a wild offset that corrupts hlock->class_idx. The subsequent reacquire_held_locks() call will invoke hlock_class() with this corrupted index, leading to a NULL or out-of-bounds pointer dereference. Add the missing NULL check, consistent with how __lock_acquire() already handles this case at the same call site.

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Meta Information

Published
2026-09-24
Last Modified
2026-09-24
Generated
2026-09-25
AI Q&A
2026-09-24
EPSS Evaluated
N/A
NVD
CVE-2026-93261
EUVD
EUVD-2026-86133

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
linux linux_kernel *

Helpful Resources

Exploitability

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CWE ID Description
CWE-UNKNOWN

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Executive Summary

This is a NULL pointer dereference vulnerability in the Linux kernel's locking subsystem. It occurs in the __lock_set_class() function where register_lock_class() can return NULL but the result is used in pointer arithmetic without checking. This leads to a corrupted index that later causes a NULL or out-of-bounds pointer dereference in hlock_class().

Detection Guidance

This vulnerability is specific to the Linux kernel's lockdep mechanism and may not have direct network detection methods. Monitor kernel logs for NULL pointer dereference errors or lock-related crashes. Check for kernel oops or panic messages indicating lock class corruption.

Impact Analysis

This vulnerability could cause system crashes or instability due to memory corruption. It may lead to denial-of-service conditions if exploited. Systems relying on kernel locking mechanisms could experience unexpected failures or security bypasses.

Compliance Impact

This vulnerability is a NULL pointer dereference in the Linux kernel's locking mechanism. It does not directly relate to data privacy, access control, or audit logging requirements typically addressed by GDPR or HIPAA. Compliance impact would be indirect if the vulnerability leads to system instability or crashes, potentially affecting availability of services handling regulated data.

Mitigation Strategies

Update the Linux kernel to the latest patched version. If immediate patching is not possible, avoid operations that trigger lockdep checks or excessive lock subclass usage. Monitor system stability and kernel logs for signs of lock corruption.

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