CVE-2016-9083 in Linux
Summary
by MITRE • 01/25/2023
drivers/vfio/pci/vfio_pci.c in the Linux kernel through 4.8.11 allows local users to bypass integer overflow checks, and cause a denial of service (memory corruption) or have unspecified other impact, by leveraging access to a vfio PCI device file for a VFIO_DEVICE_SET_IRQS ioctl call, aka a "state machine confusion bug."
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Analysis
by VulDB Data Team • 01/25/2023
The vulnerability described in CVE-2016-9083 resides within the Linux kernel's vfio pci driver implementation, specifically in the vfio_pci.c file. This flaw represents a critical security issue that affects kernel versions through 4.8.11, where local attackers can exploit a state machine confusion bug to manipulate the VFIO device interface. The vulnerability stems from improper handling of integer overflow checks during VFIO_DEVICE_SET_IRQS ioctl operations, creating a pathway for malicious actors to manipulate kernel memory structures and potentially escalate their privileges or cause system instability.
The technical flaw manifests as an integer overflow that occurs when processing the VFIO_DEVICE_SET_IRQS ioctl call on a VFIO PCI device file. This particular vulnerability operates through a state machine confusion mechanism where the kernel's internal state management fails to properly validate input parameters during interrupt configuration operations. The flaw allows attackers to craft malicious ioctl parameters that can cause the kernel to perform operations with incorrect integer values, leading to memory corruption that can result in system crashes or more severe consequences. This type of vulnerability falls under the CWE-190 category of Integer Overflow or Wraparound, which is classified as a common weakness in software development practices.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as local users with access to a VFIO PCI device can potentially cause memory corruption that may lead to system instability or privilege escalation. The vulnerability's exploitation requires local access to a VFIO PCI device file, making it less accessible than remote exploits but still concerning from a security standpoint since it can be leveraged by any user who has access to the system and can interact with the VFIO subsystem. The potential for unspecified other impacts suggests that this vulnerability could potentially be chained with other exploits or used to create more sophisticated attack vectors that could compromise system integrity or availability.
Mitigation strategies for CVE-2016-9083 primarily involve applying the kernel patches released by the Linux kernel development team, which address the integer overflow checks in the vfio_pci.c implementation. System administrators should ensure that all systems running kernel versions through 4.8.11 are updated to patched versions. Additionally, organizations should implement principle of least privilege controls to limit access to VFIO PCI device files and consider disabling VFIO functionality if it is not required for the system's operation. From an ATT&CK framework perspective, this vulnerability aligns with techniques involving privilege escalation and denial of service, and should be monitored as part of comprehensive security posture assessments. The vulnerability also highlights the importance of proper input validation and state machine design in kernel-level code, emphasizing the need for rigorous code review processes and security testing for kernel subsystems that handle device access and configuration operations.