CVE-2026-64173 in Linux
Summary
by MITRE • 07/19/2026
In the Linux kernel, the following vulnerability has been resolved:
tracing: Do not call map->ops->elt_free() if elt_alloc() fails
In paths where tracing_map_elt_alloc() failed to allocate objects, the map->ops->elt_alloc() call was never successful. In this case, map->ops->elt_free() should not be called.
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Analysis
by VulDB Data Team • 07/20/2026
This vulnerability resides within the Linux kernel's tracing subsystem and represents a classic null pointer dereference scenario that could lead to system instability or potential privilege escalation. The issue manifests in the tracing_map_elt_alloc function where memory allocation failures are not properly handled, creating a condition where the kernel attempts to free memory that was never successfully allocated. This flaw occurs during the tracing map element management process where the system allocates memory for trace data structures and subsequently attempts cleanup operations without proper validation of the allocation status.
The technical root cause stems from improper error handling in the tracing subsystem's memory management logic. When tracing_map_elt_alloc() fails to allocate memory for trace elements, the code path continues to execute map->ops->elt_free() function calls even though no valid memory was allocated to free. This creates a situation where the kernel attempts to dereference potentially invalid memory addresses or invoke cleanup routines on uninitialized data structures. The vulnerability directly relates to CWE-476 which describes null pointer dereference conditions, and more specifically aligns with CWE-835 which addresses infinite loops or infinite recursion caused by improper error handling.
The operational impact of this vulnerability extends beyond simple system crashes, potentially enabling attackers to exploit the memory management inconsistency for privilege escalation or denial of service attacks. When the tracing subsystem is actively used for performance monitoring or debugging purposes, the failure to properly handle allocation errors could result in kernel panics that require system reboot. Attackers with access to systems running affected kernels could potentially leverage this vulnerability to cause system instability or in some cases gain elevated privileges through crafted trace data manipulation.
Mitigation strategies should focus on ensuring proper error handling in the tracing subsystem's memory management code. The fix requires implementing validation checks before calling cleanup functions, ensuring that map->ops->elt_free() is only invoked when map->ops->elt_alloc() has successfully completed. System administrators should prioritize applying kernel updates that contain the patched tracing subsystem code, which typically includes proper conditional logic to prevent the execution of cleanup routines on failed allocation paths. Organizations monitoring system stability should also implement enhanced logging for tracing subsystem errors and consider disabling non-critical tracing features until patch validation is complete.
The vulnerability demonstrates how seemingly simple memory management errors in kernel code can create significant security implications, particularly when dealing with debugging and monitoring subsystems that are often enabled in production environments. This type of flaw commonly appears in complex kernel subsystems where multiple allocation and deallocation operations must be carefully coordinated to prevent resource leaks or invalid memory access patterns. The ATT&CK framework would categorize this under T1059.006 for system binary execution and potentially T1489 for system shutdown/reboot conditions, depending on the specific exploitation vector used by adversaries.
This vulnerability highlights the critical importance of proper error handling in kernel space programming where memory allocation failures can cascade into more serious security issues. The tracing subsystem's interaction with other kernel components makes this particularly dangerous as it affects core system monitoring capabilities that are essential for both debugging and security auditing operations. Regular kernel patching programs should include specific attention to tracing subsystem updates, as these often contain fixes for subtle memory management edge cases that can have far-reaching implications for system stability and security posture.
The resolution of this vulnerability typically involves implementing proper conditional logic in the tracing_map_elt_alloc function where the code checks the allocation status before proceeding with cleanup operations. This approach ensures that resources are only freed when they were actually allocated, preventing the null pointer dereference conditions that could lead to system instability. The fix pattern aligns with best practices established in kernel security guidelines and represents a fundamental requirement for robust memory management in kernel space code.