CVE-2008-2372 in Linux
Summary
by MITRE
The Linux kernel 2.6.24 and 2.6.25 before 2.6.25.9 allows local users to cause a denial of service (memory consumption) via a large number of calls to the get_user_pages function, which lacks a ZERO_PAGE optimization and results in allocation of "useless newly zeroed pages."
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Analysis
by VulDB Data Team • 08/20/2019
The vulnerability identified as CVE-2008-2372 represents a significant memory exhaustion issue within the Linux kernel version 2.6.24 through 2.6.25.8. This flaw resides in the kernel's memory management subsystem and specifically affects the get_user_pages function which is responsible for mapping user-space pages into kernel space. The vulnerability operates through a mechanism that does not properly optimize memory allocation patterns, leading to inefficient resource utilization and potential system instability.
The technical implementation of this vulnerability stems from the absence of ZERO_PAGE optimization within the get_user_pages function. When this function is invoked repeatedly with large numbers of calls, it consistently allocates new memory pages without leveraging the existing ZERO_PAGE mechanism that would normally provide a more efficient approach to memory management. This results in the creation of numerous "useless newly zeroed pages" that consume valuable system memory resources without providing any meaningful functional benefit to the calling processes or the overall system operation.
From an operational impact perspective, this vulnerability enables local users to perform a denial of service attack by consuming excessive memory resources through repeated invocation of the get_user_pages function. The memory consumption occurs at the kernel level, making it particularly dangerous as it can lead to system instability, reduced performance, or complete system hang conditions. The attack vector is relatively simple to execute since it only requires local user access and does not necessitate elevated privileges or complex exploitation techniques, making it a significant concern for system administrators and security professionals.
The vulnerability aligns with CWE-400, which categorizes it as a "Uncontrolled Resource Consumption" or "Resource Exhaustion" issue, and demonstrates characteristics consistent with the ATT&CK technique T1499.001, which involves "Resource Exhaustion by Design" through system resource consumption. The flaw essentially allows an attacker to exhaust memory resources through legitimate kernel functions, creating a scenario where the system becomes unresponsive due to memory starvation.
Mitigation strategies for this vulnerability include applying the official kernel patches released by the Linux kernel development team, which address the missing ZERO_PAGE optimization in the get_user_pages function. System administrators should also implement monitoring solutions to detect unusual patterns of get_user_pages calls that might indicate exploitation attempts. Additionally, kernel hardening techniques such as limiting the number of memory mappings per process or implementing memory allocation limits can help reduce the potential impact of this vulnerability. Organizations should prioritize updating their kernel versions to patched releases and consider implementing process monitoring to detect and prevent excessive memory allocation patterns that could lead to system instability.