CVE-2017-8064 in Linux
Summary
by MITRE
drivers/media/usb/dvb-usb-v2/dvb_usb_core.c in the Linux kernel 4.9.x and 4.10.x before 4.10.12 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.
Statistical analysis made it clear that VulDB provides the best quality for vulnerability data.
Analysis
by VulDB Data Team • 12/02/2022
The vulnerability identified as CVE-2017-8064 resides within the Linux kernel's digital video broadcasting over usb version 2 subsystem specifically in the dvb_usb_core.c file. This flaw affects kernel versions 4.9.x and 4.10.x prior to 4.10.12 and represents a critical issue that can be exploited by local attackers to compromise system stability. The vulnerability manifests when the kernel's CONFIG_VMAP_STACK option is enabled, creating a dangerous interaction that can lead to system crashes or memory corruption. The root cause stems from improper handling of DMA scatterlists when multiple virtual pages are utilized, which creates a fundamental flaw in the memory management subsystem's interaction with hardware devices.
The technical implementation of this vulnerability involves the kernel's virtual memory management system when it processes DMA operations for digital video broadcasting devices. When CONFIG_VMAP_STACK is enabled, the kernel allocates memory using virtual mapping techniques that can conflict with how the dvb-usb-v2 subsystem manages scatterlist entries for data transfer operations. The issue occurs because the kernel fails to properly account for the virtual page boundaries when multiple pages are required for a single DMA transaction, leading to memory corruption patterns that can result in kernel panics or system instability. This particular flaw falls under the CWE-121 category of stack-based buffer overflow, though it manifests in a more complex memory management context rather than traditional stack corruption.
The operational impact of CVE-2017-8064 extends beyond simple denial of service scenarios, potentially enabling more sophisticated attacks depending on the system configuration and attack surface. Local users can exploit this vulnerability to either crash the system entirely through kernel memory corruption or to create conditions that might allow for privilege escalation in certain configurations. The vulnerability's exploitation requires local access and knowledge of the specific kernel configuration, making it less immediately dangerous than remote exploits but still highly concerning for systems where local privilege escalation is a concern. The memory corruption patterns can be leveraged to create inconsistent system states that may persist across reboots or could be used to establish footholds for more advanced attacks, particularly in embedded systems or servers where the dvb-usb subsystem is actively used.
Mitigation strategies for CVE-2017-8064 primarily focus on kernel version updates and configuration management. The most effective solution involves upgrading to kernel versions 4.10.12 or later where the vulnerability has been patched through proper handling of DMA scatterlist operations when virtual memory mapping is enabled. System administrators should also consider disabling CONFIG_VMAP_STACK if the system does not require the virtual memory mapping features, though this may impact other kernel functionalities. Additionally, monitoring for unusual system crashes or memory corruption patterns can help identify potential exploitation attempts. The vulnerability aligns with ATT&CK technique T1068 by potentially enabling privilege escalation and T1499 by providing denial of service capabilities. Organizations should implement comprehensive patch management procedures to ensure all affected kernel versions are updated promptly, particularly in environments where local access controls may be insufficient. The fix implemented in the patched kernel versions properly validates scatterlist entries and ensures proper memory boundary handling when virtual pages are utilized for DMA operations, preventing the memory corruption patterns that led to system instability.