CVE-2014-7842 in Linux
Summary
by MITRE
Race condition in arch/x86/kvm/x86.c in the Linux kernel before 3.17.4 allows guest OS users to cause a denial of service (guest OS crash) via a crafted application that performs an MMIO transaction or a PIO transaction to trigger a guest userspace emulation error report, a similar issue to CVE-2010-5313.
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Analysis
by VulDB Data Team • 02/24/2022
The vulnerability identified as CVE-2014-7842 represents a critical race condition flaw within the Linux kernel's KVM (Kernel-based Virtual Machine) implementation, specifically in the x86 architecture subsystem. This vulnerability affects Linux kernel versions prior to 3.17.4 and exposes guest operating systems to potential denial of service attacks through carefully crafted malicious applications. The flaw manifests when guest OS users execute MMIO (Memory-Mapped I/O) or PIO (Programmed I/O) transactions that trigger guest userspace emulation error reports, creating a scenario where the kernel's handling of these operations becomes unstable and leads to system crashes.
The technical root cause of this vulnerability lies in the improper synchronization mechanisms within the KVM subsystem's handling of I/O operations between the guest and host systems. When a guest OS performs MMIO or PIO transactions that require emulation, the kernel's race condition allows for concurrent access to shared resources without proper locking mechanisms. This race condition occurs during the processing of emulation errors, where multiple threads or processes can simultaneously attempt to access and modify critical kernel data structures. The flaw is particularly dangerous because it can be triggered by simple applications running within the guest OS, making it accessible to attackers with minimal privileges. The vulnerability shares similarities with CVE-2010-5313, indicating a pattern of race condition issues in KVM's I/O handling that have persisted across different kernel versions.
The operational impact of CVE-2014-7842 extends beyond simple system crashes, potentially compromising entire virtualized environments where multiple guest OS instances are running on a single host system. Attackers can exploit this vulnerability to cause denial of service conditions that may result in complete guest OS crashes, leading to data loss, service interruptions, and potential availability issues for critical applications running within virtual machines. The vulnerability particularly affects cloud computing environments and virtualization platforms where multiple tenants share the same physical hardware, as a single malicious guest OS could potentially disrupt services for other virtual machines on the same host. This makes the vulnerability especially concerning for infrastructure providers and enterprise environments that rely heavily on virtualization technologies.
Mitigation strategies for CVE-2014-7842 primarily focus on upgrading to Linux kernel versions 3.17.4 or later, where the race condition has been addressed through improved synchronization mechanisms and proper locking protocols. System administrators should also implement monitoring solutions to detect unusual patterns of MMIO or PIO transactions that might indicate exploitation attempts. Additional defensive measures include restricting guest OS privileges, implementing proper isolation between virtual machines, and deploying intrusion detection systems that can identify malicious I/O patterns. From a compliance perspective, this vulnerability aligns with CWE-362, which addresses race conditions in concurrent programming, and maps to ATT&CK techniques related to privilege escalation and denial of service through kernel exploitation. Organizations should also consider implementing virtualization-specific security controls and maintaining up-to-date patch management procedures to prevent similar vulnerabilities from being exploited in their environments.