CVE-2017-8070 in Linux
Summary
by MITRE
drivers/net/usb/catc.c in the Linux kernel 4.9.x before 4.9.11 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 • 08/25/2024
The vulnerability identified as CVE-2017-8070 resides within the Linux kernel's network driver implementation, specifically in the catc.c file that handles USB network adapters. This flaw manifests when the kernel operates with the CONFIG_VMAP_STACK configuration option enabled, creating a dangerous interaction that can be exploited by local attackers to compromise system stability. The issue affects Linux kernel versions 4.9.x prior to 4.9.11, representing a significant security gap that could be leveraged for system disruption.
The technical root cause of this vulnerability stems from improper handling of DMA scatterlists when multiple virtual pages are utilized for a single DMA operation. When CONFIG_VMAP_STACK is enabled, the kernel allocates stack memory across multiple virtual pages, but the catc.c driver fails to correctly account for this memory layout when processing USB network traffic. This mismanagement occurs during the scatter-gather list construction process where the driver incorrectly calculates memory addresses and page boundaries, leading to potential memory corruption scenarios.
The operational impact of this vulnerability extends beyond simple denial of service conditions to potentially encompass more severe consequences including system crashes and memory corruption. Local users with access to the system can exploit this weakness by triggering specific network operations that force the kernel to process DMA scatterlists across multiple virtual pages. The vulnerability's exploitation can result in kernel panics, system lockups, or even data corruption within the kernel's memory management subsystem. The unspecified other impacts referenced in the CVE description suggest that the memory corruption could potentially be leveraged for more advanced exploitation techniques.
This vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and demonstrates the risks associated with improper memory management in kernel space. The attack pattern follows the ATT&CK technique T1068, which involves local privilege escalation through kernel vulnerabilities, though in this case the exploitation is limited to local users rather than requiring remote access. The flaw represents a classic example of how kernel configuration options can create unexpected interactions that compromise system security and stability.
Mitigation strategies for CVE-2017-8070 primarily involve upgrading to Linux kernel version 4.9.11 or later where the issue has been resolved through proper handling of virtual page boundaries in DMA operations. System administrators should also consider disabling CONFIG_VMAP_STACK if the functionality is not required, though this may impact other kernel features. Additionally, monitoring systems should be implemented to detect unusual kernel memory access patterns that might indicate exploitation attempts. The fix implemented in the patched kernel versions ensures that DMA scatterlists are properly managed regardless of stack allocation methods, preventing the memory corruption scenarios that could lead to system instability or potential privilege escalation.