CVE-2026-97499 in Linux
Summary
by MITRE • 09/24/2026
In the Linux kernel, the following vulnerability has been resolved:
coresight: perf: Retrieve path and source from event data
ETM perf callbacks currently use the per-CPU csdev_src pointer, which can race with updates during device registration and unregistration.
The AUX setup already builds and stores the path in the event data. Use this path to retrieve the source instead of csdev_src to avoid the race.
Export coresight_get_source() and add etm_event_get_ctxt_path() to retrieve the context's path and its source with READ_ONCE() / WRITE_ONCE() accessors. Give the comments to explain why this approach is safe when pause or resume callbacks preempt the disable callback (e.g. via NMI).
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Analysis
by VulDB Data Team • 09/24/2026
The Linux kernel coresight subsystem, which provides hardware-based tracing capabilities for performance analysis and debugging, contained a concurrency vulnerability within its ETM perf callbacks. The core issue stemmed from the reliance on the per-CPU csdev_src pointer to determine the source of trace events. This pointer is subject to modification during device registration and unregistration operations, creating a window where concurrent access could lead to race conditions. Specifically, when multiple threads or interrupt contexts attempt to read or write this shared state without proper synchronization mechanisms, the system risks accessing stale or invalid data structures, potentially leading to kernel panics, incorrect performance metrics, or security vulnerabilities related to memory safety and integrity.
To resolve this issue, developers modified the event handling logic to utilize path and source information already embedded within the event data structure during AUX setup. This approach eliminates the dependency on the volatile per-CPU csdev_src pointer by directly retrieving the necessary context from the event itself. The solution involves exporting the coresight_get_source function and introducing a new helper, etm_event_get_ctxt_path, which retrieves both the context path and its associated source using READ_ONCE and WRITE_ONCE accessors. These atomic access macros ensure that reads and writes are performed in a manner that prevents partial updates from being observed by other threads, thereby maintaining data consistency even under high-concurrency scenarios involving preemption or interrupt handling.
The technical significance of this fix lies in its alignment with established concurrency best practices for kernel development. By leveraging READ_ONCE and WRITE_ONCE, the code ensures memory ordering constraints are respected, preventing compiler optimizations that might reorder accesses and exacerbate race conditions. This is particularly critical because pause or resume callbacks can preempt disable callbacks, such as when triggered via Non-Maskable Interrupts (NMI). The added comments explicitly document why this approach remains safe in these edge cases, providing clarity for future maintainers regarding the synchronization guarantees provided by the atomic accessors and the structural integrity of the event data.
From a security perspective, this vulnerability falls under CWE-362: Concurrent Execution using Shared Resource with Improper Synchronization. The race condition allowed potential exploitation through timing attacks or memory corruption if an attacker could influence the registration/unregistration lifecycle while trace events were being processed. Mitigation involves applying the kernel patch that implements these changes to ensure thread-safe access to tracing resources. Additionally, organizations should monitor for updates to the Linux kernel coresight subsystem and apply security advisories promptly. Regular auditing of concurrent code paths using static analysis tools can help identify similar synchronization issues before they reach production environments.
The resolution also enhances the robustness of performance monitoring infrastructure by ensuring that trace data accurately reflects the hardware state without interference from control plane operations. This improvement supports reliable forensic analysis and system profiling, which are essential for maintaining operational integrity in critical systems. By decoupling event source identification from dynamic device lifecycle management, the kernel reduces complexity and potential failure points within the tracing subsystem. Future developments should continue to prioritize atomic access patterns and clear documentation of concurrency assumptions to maintain stability as hardware features evolve.