CVE-2011-3637 in Linux
Summary
by MITRE
The m_stop function in fs/proc/task_mmu.c in the Linux kernel before 2.6.39 allows local users to cause a denial of service (OOPS) via vectors that trigger an m_start error.
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Analysis
by VulDB Data Team • 03/20/2021
The vulnerability described in CVE-2011-3637 represents a critical flaw in the Linux kernel's memory management subsystem that affects versions prior to 2.6.39. This issue resides within the m_stop function located in the fs/proc/task_mmu.c file, which is responsible for managing memory mappings in the /proc filesystem. The vulnerability manifests when specific error conditions occur during memory management operations, particularly when the m_start function encounters problematic vectors that trigger an error state. This flaw falls under the category of improper error handling within kernel space operations, creating a potential pathway for denial of service attacks that can destabilize the entire system.
The technical implementation of this vulnerability exploits a race condition or improper state management within the kernel's memory management interface. When the m_stop function processes memory mapping data structures, it fails to properly handle error conditions that arise from malformed or unexpected input vectors during the m_start phase of memory iteration. This creates an OOPS condition, which is a kernel-level panic that results in system instability and typically requires a system reboot to recover. The vulnerability is classified as a local privilege escalation vector since it requires local access to the system but can be leveraged to cause system-wide denial of service. According to CWE standards, this represents a CWE-248: Uncaught Exception, where an exception or error condition is not properly handled, leading to system instability.
The operational impact of CVE-2011-3637 extends beyond simple denial of service, as it can be exploited to disrupt critical system operations and potentially compromise system availability. Attackers with local access can craft specific memory mapping requests that trigger the error path in the kernel's memory management code, causing the system to crash and display kernel oops messages. This vulnerability is particularly concerning because it operates at the kernel level where errors can have cascading effects on system stability. The ATT&CK framework categorizes this under privilege escalation techniques, specifically leveraging kernel vulnerabilities to gain unauthorized system control. In production environments, this vulnerability can be exploited by malicious local users to repeatedly crash system processes, making it a significant threat to system reliability and availability.
Mitigation strategies for CVE-2011-3637 primarily focus on immediate kernel version updates and system hardening measures. The most effective remediation involves upgrading to Linux kernel version 2.6.39 or later, where the vulnerability has been patched through improved error handling in the m_stop function. System administrators should also implement monitoring solutions to detect unusual kernel oops patterns that might indicate exploitation attempts. Additional defensive measures include restricting local user access where possible, implementing proper system logging for kernel-level activities, and conducting regular security assessments of kernel components. The patch for this vulnerability specifically addresses the improper error handling by ensuring that the m_stop function properly validates memory mapping states before attempting to process them, thereby preventing the OOPS condition that leads to system instability.