CVE-2007-5494 in Red Hat
Summary
by MITRE
Memory leak in the Red Hat Content Accelerator kernel patch in Red Hat Enterprise Linux (RHEL) 4 and 5 allows local users to cause a denial of service (memory consumption) via a large number of open requests involving O_ATOMICLOOKUP.
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Analysis
by VulDB Data Team • 08/01/2019
The vulnerability identified as CVE-2007-5494 represents a critical memory leak flaw within the Red Hat Content Accelerator kernel patch implementation on Red Hat Enterprise Linux versions 4 and 5. This issue specifically manifests when the system processes a large volume of open requests utilizing the O_ATOMICLOOKUP flag, creating a condition where kernel memory becomes progressively consumed without proper release mechanisms. The vulnerability operates at the kernel level, exploiting the improper handling of memory allocation within the content accelerator subsystem that manages file system operations and caching mechanisms. The flaw resides in the kernel's file descriptor management and memory allocation routines, where the system fails to properly deallocate memory resources after processing atomic lookup operations, leading to gradual memory exhaustion.
The technical exploitation of this vulnerability occurs when local users submit numerous concurrent open requests that utilize the O_ATOMICLOOKUP flag, which is designed for atomic file system operations. This flag triggers a specific code path within the kernel that handles file lookups and caching in a manner that does not properly clean up allocated memory structures. The memory leak accumulates over time as each atomic lookup operation allocates kernel memory but fails to release it, creating a gradual degradation of system performance. The vulnerability is classified under CWE-401 as a failure to release memory resources, specifically manifesting as a memory leak in kernel space. This type of memory exhaustion attack directly impacts system availability and can be classified under the ATT&CK technique T1499.1 for Resource Exhaustion, where adversaries consume system resources to prevent legitimate use.
The operational impact of this vulnerability extends beyond simple denial of service, as it can lead to complete system instability and potential crashes when memory consumption reaches critical levels. Local users with minimal privileges can exploit this weakness to systematically consume available kernel memory, eventually causing the system to become unresponsive or requiring forced reboot to recover. The vulnerability affects systems running RHEL 4 and 5 versions where the Content Accelerator kernel patch is installed, making it particularly concerning for enterprise environments that rely on these older but still operational systems. The memory leak can be particularly problematic in server environments where continuous file operations and caching are essential for performance, as the gradual memory consumption can go unnoticed until system performance degrades significantly. Additionally, the vulnerability may compound other memory-related issues in the system, creating cascading effects that can impact overall system stability and application performance.
Mitigation strategies for CVE-2007-5494 require immediate patch application from Red Hat, as the vulnerability exists in kernel-level code that cannot be effectively addressed through configuration changes alone. Organizations should prioritize updating their RHEL 4 and 5 systems to versions that include the fixed kernel patches, which properly implement memory deallocation routines for atomic lookup operations. System administrators should also consider implementing monitoring solutions that track memory consumption patterns to detect potential exploitation attempts before they cause system degradation. The patch addresses the root cause by ensuring proper memory cleanup in the file system operation handling code, specifically modifying the kernel's atomic lookup implementation to release allocated resources appropriately. For environments where patching is not immediately feasible, temporary workarounds may include limiting the number of concurrent file operations or implementing resource limits on user processes, though these measures only provide partial protection against the memory exhaustion attack. Organizations should also review their system logs for unusual patterns of file operations that might indicate exploitation attempts and implement proper incident response procedures to address potential memory leak exploitation scenarios.