CVE-2025-38297 in Linux
Summary
by MITRE • 07/10/2025
In the Linux kernel, the following vulnerability has been resolved:
PM: EM: Fix potential division-by-zero error in em_compute_costs()
When the device is of a non-CPU type, table[i].performance won't be
initialized in the previous em_init_performance(), resulting in division by zero when calculating costs in em_compute_costs().
Since the 'cost' algorithm is only used for EAS energy efficiency calculations and is currently not utilized by other device drivers, we should add the _is_cpu_device(dev) check to prevent this division-by-zero issue.
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Analysis
by VulDB Data Team • 12/07/2025
The vulnerability described in CVE-2025-38297 represents a critical division-by-zero error within the Linux kernel's Power Management subsystem, specifically affecting the Energy Model (EM) implementation. This flaw exists in the em_compute_costs() function where the kernel attempts to perform arithmetic operations without proper validation of input parameters. The issue manifests when processing devices that are not CPU types, creating a scenario where the performance table element remains uninitialized, leading to mathematical operations that cannot be completed due to division by zero. Such errors in kernel space can result in system crashes, denial of service conditions, or potentially exploitable states that compromise system stability and security.
The technical root cause of this vulnerability lies in the improper initialization of performance data structures within the Energy Model framework. When em_init_performance() is called for non-CPU devices, the table[i].performance field remains uninitialized, yet subsequent calls to em_compute_costs() assume these values are properly set. This fundamental flaw violates basic programming principles and kernel security practices, as the code does not validate preconditions before performing mathematical operations. The absence of proper input validation creates an exploitable condition where malicious actors could potentially trigger this division-by-zero scenario through device enumeration or power management operations, leading to system instability. This vulnerability directly maps to CWE-369, which specifically addresses the division by zero error condition, and represents a classic example of inadequate error handling in kernel space operations.
The operational impact of this vulnerability extends beyond simple system crashes, as it affects the Energy Aware Scheduling (EAS) functionality that relies on accurate cost calculations for efficient resource allocation. When the division-by-zero error occurs, the entire power management subsystem can become compromised, potentially causing the kernel to panic and reboot the system. This disruption affects not only the immediate device being processed but can cascade through the entire system's power management infrastructure, impacting CPU scheduling decisions and overall system performance. The vulnerability's limited scope to EAS energy efficiency calculations means that while the direct impact may be contained to power management operations, the broader implications include potential denial of service attacks against critical system functions that depend on proper energy management. Attackers could exploit this by manipulating device enumeration processes or by creating specific device configurations that trigger the uninitialized data access pattern.
Mitigation strategies for CVE-2025-38297 should focus on implementing proper input validation and defensive programming practices within the kernel's Energy Model implementation. The recommended fix involves adding a _is_cpu_device(dev) check before proceeding with cost calculations, ensuring that the performance data is only accessed for CPU-type devices where it has been properly initialized. This approach aligns with the principle of least privilege and defensive programming, preventing the execution path that leads to division by zero. System administrators should prioritize applying kernel updates that include this fix, as the vulnerability exists in the core power management subsystem and affects all Linux systems utilizing the Energy Model framework. Additionally, monitoring systems should be enhanced to detect unusual power management activity that might indicate exploitation attempts, and the implementation of proper kernel hardening measures including stack canaries and kernel address space layout randomization should be considered to further mitigate potential exploitation risks. The fix demonstrates the importance of proper initialization checking in kernel code and represents a standard security practice that should be applied across similar subsystems to prevent similar vulnerabilities from emerging in the future.