CVE-2017-8066 in Linux
Summary
by MITRE
drivers/net/can/usb/gs_usb.c in the Linux kernel 4.9.x and 4.10.x before 4.10.2 interacts incorrectly with the CONFIG_VMAP_STACK option, which allows local users to cause a denial of service (system crash or memory corruption) or possibly have unspecified other impact by leveraging use of more than one virtual page for a DMA scatterlist.
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Analysis
by VulDB Data Team • 12/02/2022
The vulnerability identified as CVE-2017-8066 resides within the Linux kernel's CAN (Controller Area Network) USB driver implementation, specifically in the gs_usb.c file. This flaw manifests in kernel versions 4.9.x and 4.10.x prior to the 4.10.2 release, creating a critical security concern that affects systems utilizing the CONFIG_VMAP_STACK kernel configuration option. The issue stems from improper handling of DMA scatterlists when virtual memory mapping is enabled, creating a scenario where local attackers can exploit the kernel's memory management mechanisms to trigger system instability.
The technical root cause of this vulnerability lies in the interaction between the CAN USB driver and the virtual memory management system when CONFIG_VMAP_STACK is enabled. When multiple virtual pages are required for a DMA scatterlist operation, the driver fails to properly account for the virtual memory layout, leading to memory corruption or system crashes. This occurs because the driver does not correctly handle the mapping between physical and virtual memory addresses when the kernel employs virtual memory mapping for stack allocation. The vulnerability is particularly dangerous as it operates at kernel level, allowing local users to manipulate kernel memory structures through carefully crafted DMA operations that leverage the virtual page allocation mechanism.
The operational impact of CVE-2017-8066 extends beyond simple denial of service to potentially enable more sophisticated attacks. System crashes and memory corruption can lead to complete system instability, requiring manual intervention or reboot to restore normal operation. In environments where CAN bus communication is critical for industrial control systems, automotive applications, or embedded devices, this vulnerability could result in operational failures with potentially severe consequences. The local privilege escalation aspect means that any user with access to the system can exploit this flaw, making it particularly concerning for multi-user environments where privilege separation is expected. The vulnerability aligns with CWE-121, which describes stack-based buffer overflow conditions, and may also relate to CWE-122, heap-based buffer overflow, depending on the specific memory corruption patterns observed during exploitation.
Mitigation strategies for CVE-2017-8066 focus primarily on kernel updates to version 4.10.2 or later, which contain the necessary patches to address the virtual memory handling issue in the gs_usb driver. System administrators should prioritize applying these kernel updates across all affected systems, particularly those running kernel versions 4.9.x or 4.10.x with CONFIG_VMAP_STACK enabled. Additionally, organizations can consider disabling the CONFIG_VMAP_STACK option if it is not required for their specific use cases, though this may impact system performance or functionality in other areas. Monitoring for unusual system crashes or memory corruption patterns can help detect potential exploitation attempts, and implementing proper access controls to limit local user privileges can reduce the attack surface. This vulnerability demonstrates the importance of kernel memory management validation and proper handling of virtual memory mappings in device drivers, as outlined in the ATT&CK framework's system binary modification techniques that can be leveraged for privilege escalation and system compromise.