CVE-2011-1474 in pax-linux
Summary
by MITRE
A locally locally exploitable DOS vulnerability was found in pax-linux versions 2.6.32.33-test79.patch, 2.6.38-test3.patch, and 2.6.37.4-test14.patch. A bad bounds check in arch_get_unmapped_area_topdown triggered by programs doing an mmap after a MAP_GROWSDOWN mmap will create an infinite loop condition without releasing the VM semaphore eventually leading to a system crash.
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Analysis
by VulDB Data Team • 03/17/2024
The vulnerability described in CVE-2011-1474 represents a critical denial of service flaw within the Linux kernel's memory management subsystem, specifically affecting pax-linux kernel versions 2.6.32.33-test79.patch, 2.6.38-test3.patch, and 2.6.37.4-test14.patch. This issue demonstrates a fundamental flaw in the virtual memory management implementation that can be exploited locally to cause system-wide crashes. The vulnerability arises from improper bounds checking within the arch_get_unmapped_area_topdown function, which is responsible for determining valid memory mapping regions during process memory allocation operations.
The technical root cause of this vulnerability lies in the improper handling of memory mapping operations when a program performs a MAP_GROWSDOWN mmap followed by a subsequent mmap operation. The arch_get_unmapped_area_topdown function contains a flawed bounds check that fails to properly validate memory region boundaries, creating a condition where the function enters an infinite loop. This loop occurs because the function continuously attempts to find an unmapped memory area without properly advancing its search parameters or releasing necessary system resources. The vulnerability specifically targets the virtual memory semaphore mechanism, which is crucial for coordinating memory allocation operations across multiple processes and kernel threads.
The operational impact of this vulnerability extends beyond simple system instability, as it can lead to complete system crashes and potential data loss. When the infinite loop condition is triggered, the system's memory management subsystem becomes unresponsive, causing the kernel to hang and eventually resulting in a system crash that requires manual reboot. This type of vulnerability is particularly dangerous in production environments where system uptime is critical, as it can be exploited by malicious local users to disrupt services or potentially create a persistent denial of service condition. The vulnerability affects systems running the specified pax-linux kernel versions, making it relevant to organizations using hardened kernel configurations that implement the pax security features.
The vulnerability maps directly to CWE-121, which describes heap-based buffer overflow conditions, and aligns with ATT&CK technique T1499.004, which covers system shutdown/reboot attacks. The infinite loop behavior creates a resource exhaustion scenario that can be categorized as a DoS attack vector, while the improper bounds checking represents a classic memory safety issue. Organizations should implement immediate mitigations including kernel version updates to patched releases, disabling problematic memory mapping operations where possible, and implementing monitoring systems to detect anomalous memory allocation patterns. The vulnerability also highlights the importance of proper bounds checking in kernel space operations and demonstrates why security patches must be applied promptly to prevent exploitation. System administrators should consider implementing additional security controls such as process isolation, memory limits, and regular kernel updates to prevent exploitation of similar vulnerabilities in the future.