CVE-2011-1163 in Linux
Summary
by MITRE
The osf_partition function in fs/partitions/osf.c in the Linux kernel before 2.6.38 does not properly handle an invalid number of partitions, which might allow local users to obtain potentially sensitive information from kernel heap memory via vectors related to partition-table parsing.
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Analysis
by VulDB Data Team • 10/21/2021
The vulnerability described in CVE-2011-1163 resides within the Linux kernel's partition handling mechanism, specifically in the osf_partition function located in fs/partitions/osf.c. This flaw represents a classic case of improper input validation that can lead to information disclosure vulnerabilities. The issue manifests when the kernel processes partition tables from certain disk devices, particularly those following the Open Software Foundation (OSF) partitioning scheme. The vulnerability is classified under CWE-200, which deals with improper handling of sensitive information, and falls within the broader category of information disclosure flaws that can be exploited by local attackers to gain access to kernel memory contents.
The technical flaw occurs when the osf_partition function fails to properly validate the number of partitions specified in a partition table. This function is responsible for parsing partition tables and creating partition entries in the kernel's memory space. When encountering an invalid number of partitions, the function does not implement proper bounds checking or error handling mechanisms, leading to potential memory corruption scenarios. The function essentially proceeds with processing without validating whether the partition count parameter is within acceptable limits, allowing it to access kernel heap memory beyond the intended boundaries. This improper handling creates a situation where uninitialized or previously used memory segments may be inadvertently exposed to user-space processes.
The operational impact of this vulnerability is significant for local attackers who can leverage this flaw to extract potentially sensitive information from kernel heap memory. Since the vulnerability exists in the kernel's partition parsing code, any local user with access to the system can potentially trigger the condition by interacting with specially crafted partition tables or disk devices. The information disclosed could include kernel stack contents, memory addresses, or other sensitive data that might be used for further exploitation or to aid in bypassing kernel security mechanisms. This type of information disclosure can be particularly dangerous as it may reveal kernel memory layout details that could be exploited to craft more sophisticated attacks. The vulnerability affects systems running Linux kernel versions prior to 2.6.38, making it relevant to a wide range of older systems that may still be in use.
Mitigation strategies for this vulnerability primarily involve upgrading to Linux kernel version 2.6.38 or later, where the issue has been properly addressed through enhanced input validation and proper error handling mechanisms. System administrators should prioritize patching affected systems, particularly those running older kernel versions that may be exposed to local privilege escalation risks. Additionally, implementing proper access controls and limiting local user privileges can help reduce the attack surface. The fix typically involves adding proper bounds checking to validate the number of partitions before proceeding with memory allocation and processing, ensuring that invalid inputs are properly rejected rather than processed in a manner that could expose kernel memory contents. This vulnerability demonstrates the importance of proper input validation in kernel space code and aligns with ATT&CK technique T1068, which covers local privilege escalation through kernel vulnerabilities.