CVE-2012-0879 in Linux
Summary
by MITRE
The I/O implementation for block devices in the Linux kernel before 2.6.33 does not properly handle the CLONE_IO feature, which allows local users to cause a denial of service (I/O instability) by starting multiple processes that share an I/O context.
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Analysis
by VulDB Data Team • 03/21/2021
The vulnerability identified as CVE-2012-0879 represents a critical flaw in the Linux kernel's block device I/O subsystem that existed prior to version 2.6.33. This issue specifically targets the implementation of the CLONE_IO feature within the kernel's storage handling mechanisms, creating a pathway for local attackers to disrupt system stability through strategic process management. The vulnerability operates at a fundamental level of the operating system's storage architecture, affecting how multiple processes interact with shared I/O contexts and potentially leading to system-wide instability.
The technical root cause of this vulnerability lies in the improper handling of the CLONE_IO feature within the kernel's block device layer. When multiple processes attempt to share an I/O context while utilizing the CLONE_IO functionality, the kernel fails to properly manage the synchronization and resource allocation between these processes. This mismanagement creates a condition where concurrent I/O operations can interfere with each other, leading to unpredictable behavior in the storage subsystem. The flaw manifests when processes that should operate independently begin to corrupt shared I/O context data structures, causing the kernel to become unstable during concurrent I/O operations.
The operational impact of CVE-2012-0879 extends beyond simple system performance degradation to potentially complete system instability and denial of service conditions. Local attackers can exploit this vulnerability by creating multiple processes that simultaneously share an I/O context, triggering a cascade of I/O operations that overwhelm the kernel's ability to maintain consistent state management. This vulnerability is particularly dangerous because it can be exploited using only local user privileges, making it accessible to any user with access to the system. The resulting I/O instability can cause filesystem corruption, application crashes, and in severe cases, complete system lockups that require manual intervention to resolve.
The security implications of this vulnerability align with CWE-121, which addresses memory allocation and deallocation issues in kernel space, and can be mapped to ATT&CK technique T1499.200 which covers resource exhaustion attacks targeting I/O subsystems. Organizations affected by this vulnerability should prioritize immediate kernel updates to version 2.6.33 or later, as this represents the most effective mitigation strategy. Additionally, system administrators should implement monitoring solutions that can detect unusual I/O patterns and process behavior that might indicate exploitation attempts. The vulnerability demonstrates the critical importance of proper synchronization mechanisms in kernel-level I/O handling and underscores the need for comprehensive testing of shared resource management features in operating system kernels.