CVE-2012-0038 in Linux
Summary
by MITRE
Integer overflow in the xfs_acl_from_disk function in fs/xfs/xfs_acl.c in the Linux kernel before 3.1.9 allows local users to cause a denial of service (panic) via a filesystem with a malformed ACL, leading to a heap-based buffer overflow.
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Analysis
by VulDB Data Team • 03/20/2021
The vulnerability identified as CVE-2012-0038 represents a critical integer overflow flaw within the Linux kernel's XFS filesystem implementation that fundamentally compromises system stability and availability. This issue resides in the xfs_acl_from_disk function located in the fs/xfs/xfs_acl.c source file, where improper handling of access control list data structures creates conditions ripe for exploitation. The vulnerability specifically affects Linux kernel versions prior to 3.1.9, making it a significant concern for systems running older kernel versions that remain in production environments.
The technical flaw manifests when the kernel processes filesystems containing malformed access control lists that trigger an integer overflow condition during the conversion of on-disk ACL structures to in-memory representations. This overflow occurs when the xfs_acl_from_disk function fails to properly validate the size parameters of ACL data structures, allowing maliciously crafted ACL data to cause arithmetic overflow that results in heap-based buffer overflows. The vulnerability stems from inadequate input validation and bounds checking within the kernel's filesystem processing code, creating a condition where legitimate filesystem operations can be exploited to trigger memory corruption.
The operational impact of this vulnerability extends beyond simple denial of service to potentially compromise entire system stability and availability. When exploited, the integer overflow causes the kernel to panic and crash, resulting in a complete system halt that requires manual intervention to restore normal operations. This makes the vulnerability particularly dangerous in production environments where system uptime is critical, as local users with minimal privileges can effectively disrupt services and potentially cause data loss. The heap-based buffer overflow aspect of this vulnerability also raises concerns about potential privilege escalation opportunities, though the primary impact remains denial of service.
Mitigation strategies for CVE-2012-0038 focus primarily on kernel version updates and system hardening measures. Organizations should prioritize upgrading to Linux kernel version 3.1.9 or later, which contains the necessary patches to address the integer overflow condition in the xfs_acl_from_disk function. System administrators should also implement monitoring solutions to detect unusual filesystem access patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-190, which describes integer overflow conditions, and represents a classic example of how insufficient input validation can lead to memory corruption vulnerabilities. From an ATT&CK framework perspective, this vulnerability maps to privilege escalation and denial of service techniques, as it allows local users to cause system instability through filesystem manipulation. Additionally, the vulnerability demonstrates the importance of robust input validation in kernel space code and highlights the need for comprehensive testing of filesystem handling routines to prevent similar issues from emerging in other kernel subsystems.