CVE-2004-1983 in Linux
Summary
by MITRE
The arch_get_unmapped_area function in mmap.c in the PaX patches for Linux kernel 2.6, when Address Space Layout Randomization (ASLR) is enabled, allows local users to cause a denial of service (infinite loop) via unknown attack vectors.
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Analysis
by VulDB Data Team • 11/30/2024
The vulnerability described in CVE-2004-1983 represents a critical flaw in the Linux kernel's memory management subsystem that specifically affects systems implementing PaX security patches with Address Space Layout Randomization enabled. This issue manifests as an infinite loop condition within the arch_get_unmapped_area function, which is responsible for determining appropriate memory mapping areas during process execution. The flaw occurs during the dynamic memory allocation process when applications request memory mappings through the mmap system call, creating a scenario where legitimate memory management operations can be exploited to disrupt system functionality.
The technical implementation of this vulnerability stems from improper boundary checking and memory address calculation within the arch_get_unmapped_area function in the mmap.c file. When ASLR is active, the kernel must dynamically calculate available memory regions while maintaining security properties that randomize memory layout. The flaw arises from a logic error in the address space calculation algorithm that fails to properly handle certain edge cases during memory region enumeration, leading to a condition where the function enters an infinite loop rather than returning a valid memory mapping or appropriate error code. This behavior represents a classic example of a resource exhaustion vulnerability where normal system operations consume excessive CPU cycles without making meaningful progress.
From an operational impact perspective, this vulnerability creates a reliable denial of service condition that can be exploited by local users with minimal privileges. The infinite loop consumes CPU resources continuously, potentially causing system instability, performance degradation, or complete system unresponsiveness depending on the system configuration and workload. The attack vector is particularly concerning because it requires only local user access and does not necessitate elevated privileges or network connectivity, making it accessible to any user with shell access to the affected system. This vulnerability undermines the fundamental reliability of memory management operations and can be leveraged to disrupt critical system services or applications that depend on predictable memory allocation behavior.
The vulnerability aligns with CWE-835, which specifically addresses infinite loops in software systems, and demonstrates how memory management functions can become attack surfaces when proper termination conditions are not implemented. From an ATT&CK framework perspective, this represents a privilege escalation vector through resource exhaustion techniques, potentially enabling attackers to perform system-level disruptions that could facilitate further compromise. The flaw also relates to the broader category of kernel-level memory corruption issues that can be exploited to gain unauthorized system access or cause persistent service disruption. Organizations implementing PaX security patches with ASLR enabled should prioritize this vulnerability as it directly impacts the stability and availability of systems relying on these memory protection mechanisms.
Mitigation strategies for this vulnerability include immediate patching of the kernel with the appropriate security updates that address the memory address calculation logic in arch_get_unmapped_area function. System administrators should also consider implementing additional monitoring for unusual CPU usage patterns that might indicate the infinite loop condition. The vulnerability highlights the importance of thorough testing of memory management functions, particularly in security-enhanced kernel configurations, and demonstrates the need for comprehensive validation of edge cases in kernel code. Organizations should also review their kernel configuration and security patch management procedures to ensure timely deployment of security fixes and maintain awareness of potential impacts from memory management related vulnerabilities in their system architectures.