CVE-2022-1852 in Linux
Summary
by MITRE • 06/30/2022
A NULL pointer dereference flaw was found in the Linux kernel’s KVM module, which can lead to a denial of service in the x86_emulate_insn in arch/x86/kvm/emulate.c. This flaw occurs while executing an illegal instruction in guest in the Intel CPU.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 07/17/2022
The vulnerability identified as CVE-2022-1852 represents a critical NULL pointer dereference flaw within the Linux kernel's Kernel-based Virtual Machine (KVM) module, specifically affecting the x86 emulation functionality. This issue manifests in the x86_emulate_insn function located in arch/x86/kvm/emulate.c, where the kernel fails to properly validate pointer references during the execution of illegal instructions within virtualized guest environments running on Intel CPUs. The flaw exists at the intersection of virtualization security and kernel stability, creating a potential pathway for malicious actors to disrupt system operations through carefully crafted virtual machine instructions.
The technical implementation of this vulnerability stems from inadequate input validation within the KVM subsystem's instruction emulation layer. When a guest operating system attempts to execute an illegal instruction on an Intel CPU within a virtualized environment, the kernel's emulation code does not properly check for NULL pointer conditions before dereferencing memory addresses. This condition typically occurs during the handling of complex instruction set operations where the emulation logic assumes certain pointer values will be properly initialized, but in malicious or edge-case scenarios, these pointers may remain NULL. The vulnerability is classified under CWE-476 as a NULL pointer dereference, which represents a fundamental programming error that can lead to system crashes and denial of service conditions.
From an operational perspective, this vulnerability presents a significant risk to virtualized environments where multiple guest operating systems share the same physical host. Attackers can exploit this flaw by creating malicious virtual machine configurations that trigger the execution of illegal instructions, causing the host kernel to crash and resulting in a denial of service for all virtual machines running on that system. The impact extends beyond simple system instability as it can affect cloud infrastructure providers, enterprise virtualization platforms, and any organization relying on KVM-based virtualization technologies. The vulnerability is particularly concerning because it operates at the kernel level within the hypervisor, meaning that successful exploitation can compromise the entire virtualization infrastructure rather than just individual guest instances.
The mitigation strategies for CVE-2022-1852 primarily involve applying kernel updates that contain the patched x86_emulate_insn function with proper NULL pointer validation checks. System administrators should prioritize patching affected systems, particularly those running KVM virtualization environments on Intel processors, as the vulnerability can be exploited remotely through malicious guest configurations. Additionally, organizations should implement monitoring solutions to detect unusual patterns in virtual machine instruction execution that might indicate exploitation attempts. The ATT&CK framework categorizes this vulnerability under the T1499.004 technique for Network Denial of Service, as the exploitation results in system availability disruption. Organizations should also consider implementing virtualization security best practices including regular vulnerability assessments, proper guest OS hardening, and maintaining up-to-date security patches across all virtualization components to prevent exploitation of similar vulnerabilities in the KVM subsystem.