CVE-2024-50012 in Linux
Summary
by MITRE • 10/21/2024
In the Linux kernel, the following vulnerability has been resolved:
cpufreq: Avoid a bad reference count on CPU node
In the parse_perf_domain function, if the call to of_parse_phandle_with_args returns an error, then the reference to the CPU device node that was acquired at the start of the function would not be properly decremented.
Address this by declaring the variable with the __free(device_node) cleanup attribute.
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Analysis
by VulDB Data Team • 03/22/2026
This vulnerability exists within the linux kernel's cpufreq subsystem where improper handling of device node reference counts can lead to resource management issues. The flaw occurs specifically in the parse_perf_domain function which processes performance domain configurations for cpu frequency scaling. When the of_parse_phandle_with_args function fails and returns an error condition, the code path does not properly release the previously acquired reference to the cpu device node that was obtained at the function's beginning. This creates a situation where the reference count remains incremented beyond its intended scope, potentially leading to memory leaks or resource exhaustion over time. The issue represents a classic reference counting error that can accumulate and degrade system stability under sustained load conditions.
The technical implementation of this vulnerability stems from improper resource management practices within kernel space code where device node references are acquired but not consistently released. The function begins by acquiring a reference to a cpu device node, but when error conditions occur during subsequent parsing operations, the cleanup mechanism fails to execute properly. This pattern violates fundamental kernel memory management principles and can result in dangling references that persist in memory. The vulnerability specifically relates to the absence of proper error handling cleanup routines that would normally decrement the reference count regardless of whether the primary operation succeeds or fails. Such issues are particularly dangerous in kernel space where resource leaks can directly impact system stability and potentially create denial of service conditions.
The operational impact of this vulnerability extends beyond simple memory consumption issues to potentially affect system reliability and performance. Under normal operating conditions, the leak may be negligible, but in systems with frequent cpu frequency scaling operations or high system load scenarios, the accumulated reference count errors can lead to resource exhaustion. This could manifest as degraded system performance, increased memory pressure, or in extreme cases, system instability or crashes. The vulnerability is particularly concerning in embedded systems or server environments where sustained operation and predictable resource usage are critical. Additionally, the issue could be exploited in combination with other memory-related vulnerabilities to create more severe security implications, though the direct exploitability remains limited to resource consumption scenarios.
Mitigation strategies for this vulnerability focus on ensuring proper reference count management throughout the code execution path. The recommended fix involves implementing the __free(device_node) cleanup attribute on the relevant variable declaration, which automatically ensures that device node references are properly released regardless of execution path taken. This approach aligns with established kernel development practices and follows the principle of resource acquisition is initialization where cleanup is guaranteed through proper attribute usage. System administrators should prioritize applying the kernel patches that address this specific reference counting issue, particularly in production environments where cpu frequency scaling is actively utilized. Regular monitoring of system resource usage and kernel log analysis should be implemented to detect potential manifestations of this issue. The fix also emphasizes the importance of thorough error handling in kernel code and demonstrates how seemingly minor reference counting issues can have significant operational impacts on system stability and resource management.