CVE-2026-72012 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
tracing/osnoise: Call synchronize_rcu() when unregistering
This ensures that any RCU readers traversing the instance list have finished, before releasing the reference on the tracer that the instance points to.
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Analysis
by VulDB Data Team • 09/02/2026
The vulnerability in question relates to a race condition within the Linux kernel's tracing subsystem, specifically in the osnoise tracer component. This issue arises during the process of unregistering tracing instances and involves the improper handling of RCU (Read-Copy-Update) synchronization mechanisms. The osnoise tracer is designed to monitor and measure noise in system timing, particularly focusing on interruptions that affect real-time performance. When tracing instances are unregistered, the kernel must ensure that all active readers have completed their operations before releasing memory references to prevent use-after-free conditions.
The technical flaw stems from insufficient RCU synchronization during the unregistering process of osnoise tracer instances. In concurrent systems where multiple threads may be reading from shared data structures while other threads attempt to modify or free that same data, proper synchronization is essential to maintain system integrity. Without adequate synchronization points, there exists a window where RCU readers might still be traversing the instance list when the associated tracer reference is released, leading to potential memory corruption or undefined behavior. This type of vulnerability falls under the broader category of race conditions and can be classified as a CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization.
The operational impact of this vulnerability extends beyond simple system instability to potentially compromise the entire kernel's integrity during tracing operations. When an attacker can manipulate the timing of unregister calls or trigger specific sequences that expose this race condition, they might be able to cause system crashes, data corruption, or in severe cases, privilege escalation through memory corruption techniques. The vulnerability affects systems that utilize the osnoise tracer for performance monitoring and real-time system analysis, particularly those running kernel versions where this fix has not been applied. This scenario aligns with ATT&CK technique T1059.006 for kernel-level exploitation and could be leveraged in advanced persistent threat scenarios where attackers seek to maintain persistence through kernel manipulation.
The fix implemented involves adding a call to synchronize_rcu() before releasing references to tracer instances during the unregistering process. This ensures that all RCU readers that were traversing the instance list have completed their operations before any memory deallocation occurs. The synchronization mechanism effectively creates a barrier that prevents further read-side critical sections from accessing freed memory, thereby eliminating the race condition. This approach follows established kernel development practices for managing RCU synchronization and aligns with the broader security principles of proper resource management and concurrent access control. The solution demonstrates adherence to defensive programming techniques and proper kernel subsystem design patterns that prevent common concurrency-related vulnerabilities in operating system components.
Systems administrators should prioritize applying this kernel update across all environments where tracing capabilities are utilized, particularly in mission-critical infrastructure where real-time performance monitoring is essential. Regular kernel patching processes should include verification of tracing subsystem updates to maintain operational security. The vulnerability represents a classic example of how seemingly minor concurrency issues in kernel code can have significant security implications when exploited in controlled attack scenarios. Organizations implementing real-time systems or requiring precise timing measurements should pay particular attention to this fix as it directly impacts the reliability and security of their monitoring infrastructure.