CVE-2011-0711 in Linux
Summary
by MITRE
The xfs_fs_geometry function in fs/xfs/xfs_fsops.c in the Linux kernel before 2.6.38-rc6-git3 does not initialize a certain structure member, which allows local users to obtain potentially sensitive information from kernel stack memory via an FSGEOMETRY_V1 ioctl call.
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Analysis
by VulDB Data Team • 10/18/2021
The vulnerability identified as CVE-2011-0711 represents a classic information disclosure flaw within the Linux kernel's XFS filesystem implementation. This issue resides in the xfs_fs_geometry function located in fs/xfs/xfs_fsops.c, where a critical oversight in code initialization creates a pathway for unauthorized data exposure. The vulnerability specifically affects Linux kernel versions prior to 2.6.38-rc6-git3, indicating a window of exposure that spans several years of kernel development cycles. The flaw manifests through the FSGEOMETRY_V1 ioctl call, which is designed to retrieve filesystem geometry information but inadvertently leaks kernel stack memory contents due to uninitialized memory structures.
The technical nature of this vulnerability aligns with CWE-1288, which categorizes improper initialization of data structures as a significant security concern. When the xfs_fs_geometry function processes the FSGEOMETRY_V1 ioctl request, it fails to properly initialize all structure members before returning data to user space. This incomplete initialization means that portions of kernel stack memory, which may contain sensitive data from previous operations, remain accessible through the ioctl interface. The uninitialized memory could potentially contain cryptographic keys, session tokens, network credentials, or other confidential information that was previously stored in the kernel's memory space.
From an operational perspective, this vulnerability represents a local privilege escalation vector that could be exploited by unprivileged users on a system. While it does not provide direct execution capabilities or remote access, the information disclosure aspect poses significant risks to system security. Attackers could leverage this vulnerability to gather sensitive kernel memory contents that might reveal system configuration details, memory layout information, or other data that could aid in crafting more sophisticated attacks. The impact extends beyond simple information leakage as the leaked data could be used for further exploitation attempts, including bypassing security mechanisms or conducting advanced persistent threat operations.
The exploitation of this vulnerability demonstrates the critical importance of proper memory initialization practices in kernel space code. This flaw exemplifies ATT&CK technique T1005 by enabling data collection through kernel memory access, and T1059 by potentially providing attackers with information that could be used to develop more targeted attacks. Security practitioners should recognize this vulnerability as a reminder of the importance of thorough code review processes, particularly when dealing with kernel-level memory management and ioctl interface implementations. The vulnerability also highlights the need for comprehensive testing of all code paths, especially those involving user-space kernel communication mechanisms.
Mitigation strategies for CVE-2011-0711 primarily involve upgrading to Linux kernel versions 2.6.38-rc6-git3 or later, where the initialization issue has been addressed. System administrators should prioritize patching affected systems and implement monitoring for unusual ioctl activity patterns that might indicate exploitation attempts. Additionally, organizations should conduct thorough vulnerability assessments to identify other potential uninitialized memory issues in their kernel codebase. The fix implemented in the patched versions ensures that all structure members are properly initialized before data is returned to user space, eliminating the information disclosure risk while maintaining the intended functionality of the filesystem geometry interface.