CVE-2011-1090 in Linux
Summary
by MITRE
The __nfs4_proc_set_acl function in fs/nfs/nfs4proc.c in the Linux kernel before 2.6.38 stores NFSv4 ACL data in memory that is allocated by kmalloc but not properly freed, which allows local users to cause a denial of service (panic) via a crafted attempt to set an ACL.
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Analysis
by VulDB Data Team • 11/06/2021
The vulnerability described in CVE-2011-1090 represents a classic memory management flaw within the Linux kernel's Network File System version 4 implementation. This issue specifically affects the __nfs4_proc_set_acl function located in the fs/nfs/nfs4proc.c source file, which handles the processing of access control list operations in NFSv4 protocol implementations. The flaw manifests when the kernel allocates memory using kmalloc for storing NFSv4 ACL data but subsequently fails to properly release this memory through appropriate deallocation functions, creating a memory leak condition that can accumulate over time and eventually lead to system instability.
The technical nature of this vulnerability places it squarely within the domain of memory corruption and resource exhaustion issues, which are categorized under CWE-401: Improper Release of Memory and fall into the broader category of kernel-level memory management errors. When local users exploit this vulnerability by crafting specific attempts to set NFSv4 access control lists, the kernel's memory allocation mechanism becomes progressively burdened with unreleased memory blocks. This progressive memory consumption eventually leads to system panic conditions where the kernel can no longer allocate sufficient memory resources to maintain normal operations, effectively causing a denial of service scenario that impacts system availability and stability.
From an operational impact perspective, this vulnerability presents a significant risk to systems that rely heavily on NFSv4 file sharing capabilities, particularly in enterprise environments where multiple users might be performing ACL operations on shared filesystems. The local nature of the exploit means that any user with access to the system can potentially trigger the vulnerability, making it particularly dangerous in multi-user environments where privilege separation might not be strictly enforced. The resulting system panic can lead to complete system crashes, requiring manual intervention for recovery and potentially causing data loss if systems are not properly configured for graceful degradation. This vulnerability also demonstrates the critical importance of proper memory management practices in kernel-space code, as even seemingly benign operations can lead to catastrophic system failures when memory handling is inadequate.
The mitigation strategies for CVE-2011-1090 primarily involve upgrading to Linux kernel versions 2.6.38 or later, where the memory leak issue has been addressed through proper memory deallocation mechanisms in the nfs4_proc_set_acl function. System administrators should also implement monitoring solutions to detect unusual memory consumption patterns that might indicate exploitation attempts, while maintaining regular patch management schedules to ensure all kernel components remain up-to-date with security fixes. Organizations using NFSv4 services should consider implementing additional access controls and monitoring for ACL operations to limit potential exploitation vectors. This vulnerability aligns with ATT&CK technique T1499.001: Endpoint Denial of Service, specifically focusing on resource exhaustion attacks that target kernel memory management functions, and represents a fundamental security principle that proper resource management is essential for maintaining system stability and preventing exploitation of memory-related vulnerabilities in operating system kernels.