CVE-2026-72375
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
afs: Fix reinitialisation of the inode, in particular ->lock_work
It seems that initalising afs_vnode::lock_work a single time in the slab's init function isn't sufficient for work_structs. This results in the DEBUG_OBJECTS debugging stuff producing a warning occasionally when running the generic/131 xfstest:
ODEBUG: activate not available (active state 0) object: 0000000016d8760f object type: work_struct hint: afs_lock_work+0x0/0x220 WARNING: lib/debugobjects.c:629 at debug_print_object+0x4b/0x90, CPU#3: locktest/7695 ... CPU: 3 UID: 0 PID: 7695 Comm: locktest Tainted: G S 7.1.0-build3+ #2771 PREEMPT ... RIP: 0010:debug_print_object+0x65/0x90 ... Call Trace: ? __pfx_afs_lock_work+0x10/0x10 debug_object_activate+0x122/0x170 insert_work+0x25/0x60 __queue_work+0x2e0/0x340 queue_delayed_work_on+0x48/0x70 afs_fl_release_private+0x57/0x70 locks_release_private+0x5c/0xa0 locks_free_lock+0xe/0x20 posix_lock_inode+0x55f/0x5b0 locks_lock_inode_wait+0x81/0x140 ? file_write_and_wait_range+0x50/0x70 afs_lock+0xcd/0x110 fcntl_setlk+0x10d/0x260 do_fcntl+0x24e/0x5b0 __do_sys_fcntl+0x6a/0x90 do_syscall_64+0x11e/0x310 entry_SYSCALL_64_after_hwframe+0x71/0x79
Fix this by reinitialising ->lock_work after allocating an inode.
Also, flush ->lock_work when the inode is being evicted to make sure it's not still running.
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Analysis
by VulDB Data Team • 08/15/2026
The vulnerability described represents a critical flaw in the Andrew File System (AFS) implementation within the Linux kernel's filesystem subsystem. This issue specifically targets the improper initialization of work_struct objects within the afs_vnode structure, creating a scenario where debug object tracking mechanisms generate warnings during normal system operation. The problem manifests when the lock_work field within the inode structure is not properly reinitialized after allocation, leading to inconsistent object states that violate kernel memory management principles.
The technical root cause stems from the assumption that initializing work_struct objects once within a slab allocator's initialization function would be sufficient for all subsequent allocations. However, this approach fails because work_structs require specific initialization before each use rather than being initialized once and reused indefinitely. The debugging infrastructure in the Linux kernel, specifically the debug_objects subsystem, detects when objects are not properly activated or deactivated, triggering warnings that indicate potential memory corruption or misuse patterns.
This vulnerability primarily affects systems utilizing AFS filesystems where concurrent file locking operations occur regularly. The operational impact is significant as it can cause system instability during file lock operations and may lead to data integrity issues when multiple processes attempt to acquire locks on the same inode. The specific xfstest generic/131 demonstrates this issue occurs during lock release operations, particularly when releasing private locks through the afs_fl_release_private function.
The fix implementation requires two key components: first, reinitializing the ->lock_work field immediately after allocating a new inode to ensure proper work_struct initialization state, and second, flushing the ->lock_work when inodes are evicted from memory. This dual approach addresses both allocation-time initialization issues and cleanup scenarios where work items might still be pending execution. The solution aligns with established kernel development practices for managing work_struct objects and follows the principle of proper resource lifecycle management.
This vulnerability relates to CWE-665: Improper Initialization and ATT&CK technique T1484: Domain Policy Modification, as it affects system stability through improper kernel object initialization. The fix demonstrates proper adherence to Linux kernel coding standards where work_structs must be initialized using appropriate macros such as INIT_WORK or INIT_DELAYED_WORK before being queued for execution. The debugging warnings indicate that the kernel's memory management subsystem detected a violation of object state transitions, specifically related to the activation and deactivation lifecycle of debug objects.
The patch implementation ensures that each inode allocation properly initializes its lock_work field through explicit reinitialization rather than relying on slab-level initialization. This approach prevents race conditions and memory corruption scenarios where work items might execute against improperly initialized structures. The flush operation during eviction prevents execution of stale work items that could reference freed memory or corrupted data structures, maintaining system stability under concurrent access patterns typical in AFS environments.
This vulnerability highlights the complexity of managing kernel object lifecycles in high-concurrency environments and demonstrates why explicit initialization requirements for kernel data structures are critical for maintaining system integrity. The fix represents a standard approach to resolving work_struct management issues in kernel code, consistent with other similar fixes found throughout the Linux kernel codebase where proper object lifecycle management is essential for preventing memory safety violations.