CVE-2012-0058 in Linux
Summary
by MITRE
The kiocb_batch_free function in fs/aio.c in the Linux kernel before 3.2.2 allows local users to cause a denial of service (OOPS) via vectors that trigger incorrect iocb management.
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Analysis
by VulDB Data Team • 12/01/2021
The vulnerability identified as CVE-2012-0058 resides within the Linux kernel's asynchronous I/O subsystem, specifically in the kiocb_batch_free function located in fs/aio.c. This flaw represents a classic case of improper resource management that can be exploited to trigger kernel oops conditions, effectively leading to system denial of service. The vulnerability affects Linux kernel versions prior to 3.2.2, making it a significant concern for systems running older kernel versions where patching may not have been applied promptly. The issue manifests when certain vectors are processed that cause incorrect management of iocb (io control block) structures, which are fundamental components in the kernel's asynchronous I/O operations.
The technical implementation of this vulnerability stems from a flaw in how the kernel handles batch freeing of io control blocks during asynchronous I/O operations. When the kiocb_batch_free function processes vectors that contain malformed or unexpected iocb structures, it fails to properly validate the state of these control blocks before attempting to free them. This improper validation leads to a situation where the kernel attempts to access or modify memory locations that may have already been freed or are in an inconsistent state. The vulnerability is particularly dangerous because it operates at the kernel level, meaning that a local user with minimal privileges can exploit this flaw to cause the kernel to crash or enter an unrecoverable state. This behavior aligns with CWE-122, which describes improper restriction of operations within a recognized security boundary, and specifically relates to memory management errors in kernel space.
The operational impact of CVE-2012-0058 extends beyond simple system crashes as it provides a mechanism for local users to perform denial of service attacks against running systems. While the vulnerability requires local access to exploit, it represents a significant risk in environments where untrusted users have shell access to systems or where privilege escalation is possible through other means. The kernel oops condition generated by this vulnerability can result in system instability, requiring manual intervention for recovery, and potentially allowing for more sophisticated attacks if combined with other vulnerabilities. From an attacker's perspective, this vulnerability fits within the attack pattern described by ATT&CK technique T1499.004, which involves network disruption through system resource exhaustion or kernel-level manipulation. The impact is particularly severe in server environments where continuous availability is critical, as even a single successful exploitation can render the system unusable until manual restart or patching occurs.
Mitigation strategies for CVE-2012-0058 primarily focus on applying the appropriate kernel patches that address the iocb management issue in the kiocb_batch_free function. System administrators should prioritize updating to Linux kernel version 3.2.2 or later, which contains the necessary fixes for this vulnerability. Additionally, organizations should implement monitoring solutions that can detect kernel oops conditions or unusual system behavior that might indicate exploitation attempts. While there are no specific workarounds that can be applied without patching, administrators can consider implementing additional security measures such as restricting local user access where possible and ensuring that all systems are kept up to date with security patches. The vulnerability also highlights the importance of kernel security testing and the need for proper input validation in kernel space code, particularly in functions that manage kernel resources. Regular security audits of kernel code and adherence to secure coding practices can help prevent similar issues from arising in the future, making this vulnerability a valuable case study for understanding kernel-level security flaws and their implications for system stability and availability.