CVE-2016-10905 in Linux
Summary
by MITRE
An issue was discovered in fs/gfs2/rgrp.c in the Linux kernel before 4.8. A use-after-free is caused by the functions gfs2_clear_rgrpd and read_rindex_entry.
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Analysis
by VulDB Data Team • 11/26/2023
The vulnerability identified as CVE-2016-10905 represents a critical use-after-free flaw within the Linux kernel's GFS2 (Global File System 2) implementation. This issue resides in the fs/gfs2/rgrp.c source file and affects kernel versions prior to 4.8, creating a significant security risk for systems utilizing GFS2 file systems. The vulnerability stems from improper memory management within the gfs2_clear_rgrpd and read_rindex_entry functions, which handle resource group metadata operations in the distributed file system. The flaw occurs when memory allocated for resource group descriptors is freed but subsequently accessed by other functions, leading to unpredictable behavior and potential system compromise.
The technical exploitation of this vulnerability involves a specific memory management sequence where the gfs2_clear_rgrpd function releases memory structures containing resource group metadata while the read_rindex_entry function may still reference these freed memory locations. This creates a classic use-after-free condition that can be leveraged by malicious actors to execute arbitrary code with kernel privileges. The flaw is particularly dangerous because GFS2 is designed for shared storage environments where multiple nodes access the same file system, making it a prime target for attackers seeking to gain elevated privileges within clustered environments. The vulnerability aligns with CWE-416, which specifically addresses use-after-free conditions in software implementations.
From an operational perspective, systems running Linux kernel versions before 4.8 that utilize GFS2 file systems are at significant risk of exploitation. The impact extends beyond simple denial of service to potential privilege escalation and system compromise, as attackers could leverage this vulnerability to gain root access to affected systems. The attack surface is particularly broad in enterprise environments where GFS2 is commonly deployed for high-availability storage solutions and clustered computing environments. Organizations using distributed storage architectures are especially vulnerable, as the flaw could enable attackers to disrupt shared storage operations or gain unauthorized access to sensitive data across multiple nodes in a cluster. This vulnerability directly maps to several ATT&CK techniques including privilege escalation and defense evasion.
Mitigation strategies for CVE-2016-10905 primarily focus on kernel version upgrades to 4.8 or later, which contain the necessary patches to address the memory management issues in the GFS2 implementation. System administrators should prioritize patching affected systems, particularly those operating in clustered environments where GFS2 is actively used. Additionally, monitoring for suspicious file system operations and implementing proper access controls can help detect potential exploitation attempts. Organizations should also consider implementing network segmentation to limit exposure of systems utilizing GFS2, as this reduces the attack surface for potential exploitation. The fix implemented in kernel 4.8 addresses the underlying memory management issues by ensuring proper reference counting and memory deallocation sequences in the affected functions, preventing the conditions that led to the use-after-free scenario.