CVE-2008-5300 in Linux
Summary
by MITRE
Linux kernel 2.6.28 allows local users to cause a denial of service ("soft lockup" and process loss) via a large number of sendmsg function calls, which does not block during AF_UNIX garbage collection and triggers an OOM condition, a different vulnerability than CVE-2008-5029.
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Analysis
by VulDB Data Team • 08/23/2019
The vulnerability identified as CVE-2008-5300 represents a critical denial of service flaw within the Linux kernel version 2.6.28 that specifically targets the AF_UNIX socket implementation. This weakness enables local attackers to trigger system instability through a carefully crafted sequence of sendmsg function calls that exploit the kernel's garbage collection mechanisms. The vulnerability operates by overwhelming the kernel's ability to handle socket cleanup operations, leading to a soft lockup condition where the system becomes unresponsive to user input while processes are terminated unexpectedly.
The technical root cause of this vulnerability lies in the improper handling of AF_UNIX socket garbage collection during high-volume sendmsg operations. When numerous sendmsg calls are executed in rapid succession, the kernel's garbage collection process fails to properly block during cleanup operations, creating a scenario where memory allocation requests cannot be satisfied. This condition ultimately leads to an out-of-memory (OOM) situation that triggers the system's memory management subsystem to terminate processes, including critical system processes. The flaw is particularly insidious because it does not rely on external network conditions but rather exploits internal kernel mechanisms that are normally expected to handle such operations gracefully.
From an operational perspective, this vulnerability poses significant risks to system availability and stability. The soft lockup condition effectively renders the affected system unusable until manual intervention occurs, while the process loss can result in data corruption or loss of ongoing operations. The vulnerability affects systems running Linux kernel 2.6.28 and potentially earlier versions in the 2.6.x series, making it particularly concerning for enterprise environments where system uptime is critical. The impact extends beyond simple denial of service to potentially compromise the integrity of running applications and services that depend on reliable socket communication.
The security implications of CVE-2008-5300 align with CWE-400, which addresses "Uncontrolled Resource Consumption" in software systems, and can be categorized under ATT&CK technique T1499.001 for "Network Denial of Service" within the context of system resource exhaustion. This vulnerability demonstrates how improper resource management in kernel-level operations can be exploited to cause system-wide instability, particularly affecting systems with limited memory resources or those running multiple concurrent socket operations. Organizations should implement immediate mitigations including kernel updates to versions that address this specific garbage collection flaw, along with monitoring for unusual patterns of sendmsg system calls that might indicate exploitation attempts.
The remediation approach for this vulnerability requires kernel-level patches that properly implement blocking mechanisms during AF_UNIX garbage collection operations and improve memory management during high-volume socket operations. System administrators should prioritize updating to kernel versions that include fixes for this specific issue, as the vulnerability can be exploited by any local user with access to the system. Additionally, implementing process monitoring and resource limits can help mitigate the impact if exploitation occurs, though the most effective solution remains the application of the official kernel patches that address the root cause of the garbage collection failure.