CVE-2017-5548 in Linux
Summary
by MITRE
drivers/net/ieee802154/atusb.c in the Linux kernel 4.9.x before 4.9.6 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 • 11/11/2022
The vulnerability identified as CVE-2017-5548 resides within the Linux kernel's ieee802154 driver implementation, specifically in the atusb.c file that handles USB-based 802.15.4 wireless communication devices. This flaw manifests when the kernel is compiled with the CONFIG_VMAP_STACK option enabled, which allows kernel stacks to be mapped across multiple virtual pages rather than being confined to a single page. The issue represents a critical design oversight in how the driver manages DMA scatterlist operations when dealing with virtual memory mappings that span multiple pages.
The technical root cause of this vulnerability stems from improper handling of memory management operations within the USB 802.15.4 driver when virtual stack mapping is enabled. When CONFIG_VMAP_STACK is active, kernel stacks can occupy multiple virtual pages, creating a scenario where the driver's DMA scatterlist handling code fails to properly account for the virtual memory layout. This mismanagement occurs during the processing of wireless frame transmissions and receptions, where the driver attempts to map kernel memory for DMA operations. The flaw allows local attackers with kernel-level privileges to manipulate memory pointers in a way that can corrupt kernel memory structures or trigger system crashes.
The operational impact of this vulnerability extends beyond simple denial of service scenarios, as it can potentially lead to system instability and memory corruption that may be exploitable for privilege escalation. When the affected driver processes DMA operations with virtual stack mappings, the improper memory handling can cause kernel memory corruption that may result in system panics, kernel oops messages, or more subtle memory corruption issues. The vulnerability is particularly concerning because it affects the core networking subsystem and can be triggered through legitimate kernel operations, making detection and prevention challenging. This weakness aligns with CWE-121, which describes heap-based buffer overflow conditions, and represents a classic case of improper memory management in kernel space.
The mitigation strategies for CVE-2017-5548 primarily involve updating to kernel versions 4.9.6 or later where the issue has been addressed through proper memory management handling in the driver code. System administrators should also consider disabling the CONFIG_VMAP_STACK option if the functionality is not required, though this may impact system performance and memory usage patterns. Additionally, monitoring for kernel oops messages and system crashes in environments where 802.15.4 wireless devices are present can help identify exploitation attempts. Organizations should implement proper kernel patching procedures and maintain up-to-date security monitoring to detect potential exploitation attempts that could leverage this vulnerability for more advanced attacks within the ATT&CK framework's privilege escalation and persistence categories. The fix implemented in kernel 4.9.6 specifically addresses the virtual memory mapping handling in the DMA scatterlist operations, ensuring proper alignment with the virtual stack configuration while maintaining the security and stability of the kernel networking subsystem.