CVE-2026-23028 Overview
A memory leak vulnerability has been identified in the Linux kernel's KVM (Kernel-based Virtual Machine) implementation for the LoongArch architecture. The vulnerability exists in the kvm_ipi_destroy() function, which fails to properly free the kvm_device struct that was allocated during kvm_ioctl_create_device(). This oversight leads to memory leakage when KVM devices are destroyed, potentially causing resource exhaustion over time in virtualization environments.
Critical Impact
Systems running virtualized workloads on LoongArch architecture may experience gradual memory exhaustion due to improper cleanup of KVM device structures, potentially leading to denial of service conditions.
Affected Products
- Linux kernel with LoongArch KVM support
- LoongArch-based systems running KVM virtualization
- Virtualization platforms utilizing affected kernel versions
Discovery Timeline
- 2026-01-31 - CVE CVE-2026-23028 published to NVD
- 2026-02-03 - Last updated in NVD database
Technical Details for CVE-2026-23028
Vulnerability Analysis
This vulnerability is classified as a Memory Leak affecting the Linux kernel's KVM subsystem on LoongArch architecture. The issue stems from improper resource cleanup in the device destruction pathway.
When a KVM device is created via kvm_ioctl_create_device(), the kernel allocates memory for a kvm_device structure. The design expectation is that the device's destroy() callback (in this case kvm_ipi_destroy()) should be responsible for freeing this allocated memory when the device is no longer needed. However, the implementation of kvm_ipi_destroy() fails to perform this deallocation, resulting in a memory leak each time a KVM IPI device is destroyed.
In virtualization environments where KVM devices may be created and destroyed frequently, this memory leak can accumulate over time, potentially leading to memory exhaustion and system instability.
Root Cause
The root cause is an incomplete implementation of the kvm_ipi_destroy() function in the LoongArch KVM code. The function does not include the necessary kfree() call to release the kvm_device struct that was allocated during device creation. This represents a violation of the expected contract between kvm_ioctl_create_device() and the device's destroy callback, where the destroy function is responsible for cleaning up all resources associated with the device, including the device structure itself.
Attack Vector
The attack vector for this vulnerability is local, requiring access to the host system running KVM virtualization. An attacker with the ability to create and destroy KVM devices repeatedly could potentially exploit this memory leak to cause resource exhaustion, leading to a denial of service condition. The vulnerability does not provide code execution capabilities but affects system availability through memory exhaustion.
The exploitation scenario involves repeatedly creating KVM IPI devices and then destroying them, causing memory to be leaked with each destroy operation. Over time, this can deplete available system memory and impact the stability of the virtualization platform and guest VMs.
Detection Methods for CVE-2026-23028
Indicators of Compromise
- Gradual increase in kernel memory usage over time without corresponding workload increase
- Memory allocation failures in KVM subsystem logs
- System performance degradation in virtualized environments running on LoongArch
Detection Strategies
- Monitor kernel memory usage trends, particularly slab allocator statistics related to KVM structures
- Implement memory auditing tools to track kvm_device allocations and deallocations
- Review kernel logs for OOM (Out of Memory) events in KVM-related processes
Monitoring Recommendations
- Configure memory monitoring alerts for systems running LoongArch KVM workloads
- Track /proc/meminfo and /proc/slabinfo for anomalous growth patterns
- Implement periodic system health checks that include memory leak detection
How to Mitigate CVE-2026-23028
Immediate Actions Required
- Update to a patched Linux kernel version that includes the fix for kvm_ipi_destroy()
- Monitor memory usage on affected systems until patches can be applied
- Consider scheduling periodic system reboots as a temporary workaround to reclaim leaked memory
Patch Information
The Linux kernel maintainers have released patches to address this vulnerability. The fix ensures that kvm_ipi_destroy() properly frees the kvm_device structure, preventing the memory leak. Patches are available through the official kernel git repositories:
Workarounds
- Limit KVM device creation/destruction cycles where possible
- Implement memory monitoring with automated alerts for unusual growth
- Schedule maintenance windows for system reboots to reclaim leaked memory on production systems that cannot be immediately patched
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
