CVE-2017-8061 in Linux
Summary
by MITRE
drivers/media/usb/dvb-usb/dvb-usb-firmware.c in the Linux kernel 4.9.x and 4.10.x before 4.10.7 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-2017-8061 resides within the Linux kernel's digital video broadcasting over usb subsystem, specifically in the dvb-usb-firmware.c driver file. This flaw manifests in kernel versions 4.9.x and 4.10.x prior to 4.10.7 and represents a critical issue that affects systems utilizing the CONFIG_VMAP_STACK configuration option. The vulnerability stems from improper handling of DMA scatterlists when multiple virtual pages are involved, creating a fundamental mismatch between the kernel's memory management and device driver communication mechanisms.
The technical root cause of this vulnerability lies in the incorrect interaction between the virtual memory management system and the usb dvb driver's firmware loading process. When CONFIG_VMAP_STACK is enabled, the kernel maps virtual memory pages differently than when it's disabled, creating a scenario where the dvb-usb-firmware.c driver fails to properly account for the memory layout when processing scatterlist entries that span multiple virtual pages. This misalignment occurs during the firmware download process where the driver attempts to map physical memory pages into virtual addresses for usb communication, but the virtual page management system creates inconsistencies that lead to memory corruption or system instability.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to potentially encompass more severe consequences including system crashes, memory corruption, and in some cases unspecified additional security implications. Local attackers with minimal privileges can exploit this vulnerability by triggering the specific code path that handles firmware loading for dvb usb devices, causing the kernel to execute invalid memory operations or corrupt kernel data structures. The attack vector requires the target system to have the CONFIG_VMAP_STACK option enabled and to be running an affected kernel version, making it particularly relevant for embedded systems, servers, and desktop environments that utilize dvb usb hardware.
From a cybersecurity perspective, this vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and represents a classic case of improper memory management in kernel space. The ATT&CK framework categorizes this under privilege escalation and denial of service techniques, as attackers can leverage this flaw to either crash the system or potentially gain elevated privileges through memory corruption. The vulnerability demonstrates the complexity of kernel security where seemingly minor configuration options can create cascading failures in device driver implementations, highlighting the importance of thorough testing across different kernel configurations.
Mitigation strategies for CVE-2017-8061 primarily involve updating to kernel versions 4.10.7 or later where the issue has been addressed through proper handling of virtual memory page mappings during firmware loading operations. System administrators should also consider disabling the CONFIG_VMAP_STACK option if dvb usb functionality is not required, though this may impact other kernel features that depend on virtual memory management. Additionally, organizations should implement monitoring for unusual system crashes or memory errors that might indicate exploitation attempts, and maintain up-to-date kernel security patches as part of their overall security posture to prevent similar vulnerabilities from being exploited in the future.