CVE-2019-10124 in Linux
Summary
by MITRE
An issue was discovered in the hwpoison implementation in mm/memory-failure.c in the Linux kernel before 5.0.4. When soft_offline_in_use_page() runs on a thp tail page after pmd is split, an attacker can cause a denial of service (BUG).
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Analysis
by VulDB Data Team • 05/21/2020
The vulnerability identified as CVE-2019-10124 represents a critical flaw in the Linux kernel's memory management subsystem that specifically affects the hardware memory poisoning implementation. This issue resides within the mm/memory-failure.c file and impacts kernel versions prior to 5.0.4, creating a potential avenue for denial of service attacks through carefully crafted memory operations. The vulnerability manifests when the soft_offline_in_use_page() function processes transparent huge page (THP) tail pages following a pmd split operation, exposing a race condition that can lead to system instability and complete service disruption.
The technical root cause of this vulnerability stems from improper handling of memory page states during the hardware memory poisoning process. When a transparent huge page is split into smaller pages, the system must properly manage the state transitions of both the head and tail pages. The soft_offline_in_use_page() function fails to account for the specific conditions that occur when tail pages are processed after a pmd split operation, leading to a situation where the kernel encounters an unexpected state that triggers a BUG condition. This flaw operates at the kernel level and requires specific memory access patterns to be exploited, making it particularly challenging to detect and prevent through conventional security measures.
The operational impact of CVE-2019-10124 extends beyond simple system instability, as it can be leveraged by malicious actors to perform denial of service attacks against systems running vulnerable kernel versions. An attacker capable of triggering the specific sequence of memory operations required to activate this vulnerability can cause the kernel to enter an unrecoverable state, resulting in system crashes, reboot cycles, and complete service unavailability. This vulnerability particularly affects systems that utilize transparent huge pages for memory management, which are common in high-performance computing environments and server configurations where memory efficiency is prioritized.
This vulnerability aligns with CWE-121, which addresses stack buffer overflow conditions, and demonstrates characteristics consistent with memory safety issues that can lead to system crashes and denial of service scenarios. From an adversarial perspective, this flaw maps to ATT&CK technique T1499.004, which involves network denial of service attacks through system resource exhaustion, though in this case the resource exhaustion occurs at the kernel memory management level rather than network bandwidth. The vulnerability also relates to broader memory corruption patterns that have been documented in kernel security research, particularly in the context of memory failure handling mechanisms.
Mitigation strategies for CVE-2019-10124 focus primarily on kernel version updates to 5.0.4 or later, where the memory management implementation has been corrected to properly handle the edge cases involving THP tail pages after pmd splits. System administrators should prioritize patching vulnerable systems, particularly in production environments where memory-intensive operations are common. Additionally, monitoring systems should be configured to detect unusual memory management patterns that might indicate attempted exploitation of this vulnerability. Organizations utilizing transparent huge pages should implement additional memory management policies and consider disabling THP functionality if the risk of exploitation outweighs the performance benefits. The fix implemented in the patched kernel versions addresses the specific race condition in the page state management during memory failure operations, ensuring that tail pages are properly accounted for during pmd split operations.