CVE-2012-6701 in Android
Summary
by MITRE • 01/25/2023
Integer overflow in fs/aio.c in the Linux kernel before 3.4.1 allows local users to cause a denial of service or possibly have unspecified other impact via a large AIO iovec.
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Analysis
by VulDB Data Team • 01/25/2023
The vulnerability described in CVE-2012-6701 represents a critical integer overflow flaw located within the Linux kernel's asynchronous I/O subsystem at fs/aio.c. This issue affects kernel versions prior to 3.4.1 and demonstrates how improper input validation can lead to severe system instability. The vulnerability specifically manifests when processing large AIO iovec (input/output vector) structures, which are fundamental components in asynchronous I/O operations that allow applications to perform multiple I/O operations concurrently without blocking. The integer overflow occurs during the calculation of memory allocation sizes for these iovec structures, creating a condition where arithmetic operations exceed the maximum representable value for signed integers. This flaw falls under CWE-190, which categorizes integer overflow vulnerabilities, and specifically aligns with the ATT&CK technique T1499.004 for Denial of Service through resource exhaustion or memory corruption. The vulnerability is particularly dangerous because it can be exploited by local users who have access to the system, making it a significant concern for privilege escalation scenarios and system stability.
The technical exploitation of this vulnerability occurs when an attacker crafts malicious AIO iovec operations with extremely large count values that cause integer overflow during memory allocation calculations. When the kernel processes these malformed requests, the overflow results in incorrect memory allocation sizes, which can lead to memory corruption, heap corruption, or other undefined behaviors. The overflow typically occurs in the context of the io_submit system call, which is responsible for submitting asynchronous I/O operations to the kernel's AIO subsystem. The kernel's handling of the iovec structures, which contain arrays of memory addresses and lengths, becomes compromised when the integer arithmetic fails to properly validate the input parameters. This failure creates a scenario where the kernel may allocate insufficient memory for the operation or may attempt to allocate memory in a manner that corrupts adjacent memory regions. The impact extends beyond simple denial of service, as the memory corruption can potentially lead to privilege escalation opportunities or arbitrary code execution depending on the specific memory layout and the attacker's control over the system state.
The operational impact of CVE-2012-6701 is substantial across various Linux distributions and server environments that utilize asynchronous I/O operations extensively. Systems running kernel versions before 3.4.1 are vulnerable to both denial of service attacks and potential privilege escalation scenarios, making this vulnerability particularly dangerous in multi-user environments or server deployments. The vulnerability affects systems that rely heavily on AIO operations for database servers, web servers, file systems, and other applications that require high-performance asynchronous I/O handling. Attackers can exploit this vulnerability by simply executing a local process that submits malicious AIO requests with oversized iovec parameters, requiring minimal privileges and no special system access. The vulnerability's impact is amplified because it affects the core kernel functionality, meaning that successful exploitation can compromise the entire system's stability and security posture. Organizations running vulnerable kernel versions face significant risk of service disruption, data integrity issues, and potential security breaches that could allow attackers to gain elevated privileges or execute malicious code within the system's memory space.
The primary mitigation strategy for CVE-2012-6701 involves upgrading to Linux kernel version 3.4.1 or later, which contains the necessary patches to prevent the integer overflow condition in the AIO subsystem. System administrators should prioritize patching their kernel versions, particularly in production environments where the vulnerability could be exploited by malicious actors. Additionally, organizations should implement monitoring for abnormal AIO activity and consider implementing access controls to limit local user privileges where possible. The kernel patch addresses the issue by adding proper input validation and boundary checks to prevent the integer overflow condition during iovec size calculations. Security teams should also consider implementing intrusion detection systems that can identify suspicious AIO operations and monitor for potential exploitation attempts. For systems where immediate kernel upgrades are not feasible, administrators can implement temporary workarounds such as restricting AIO usage or implementing application-level controls to prevent large iovec operations. The vulnerability highlights the importance of thorough input validation in kernel space code and demonstrates how seemingly minor arithmetic errors can have significant security implications. Organizations should also conduct regular security audits of their kernel configurations and maintain up-to-date security patches to prevent similar vulnerabilities from compromising their systems. This vulnerability serves as a reminder of the critical importance of kernel security and the need for continuous monitoring and updating of system components that handle low-level memory operations.