CVE-2005-2800 in Linux
Summary
by MITRE
Memory leak in the seq_file implemenetation in the SCSI procfs interface (sg.c) in Linux kernel 2.6.13 and earlier allows local users to cause a denial of service (memory consumption) via certain repeated reads from the /proc/scsi/sg/devices file, which is not properly handled when the next() iterator returns NULL or an error.
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Analysis
by VulDB Data Team • 12/19/2024
The vulnerability described in CVE-2005-2800 represents a critical memory management flaw within the Linux kernel's SCSI subsystem, specifically affecting versions 2.6.13 and earlier. This issue resides in the seq_file implementation of the SCSI procfs interface, where the sg.c driver fails to properly handle iterator states during file read operations. The vulnerability manifests when local users repeatedly access the /proc/scsi/sg/devices file, triggering a memory leak that gradually consumes system resources and ultimately leads to denial of service conditions. The root cause stems from inadequate error handling within the iterator mechanism that governs how data is presented through the procfs interface, creating a scenario where allocated memory is not properly released during abnormal termination conditions.
The technical implementation of this vulnerability demonstrates a classic memory leak pattern within kernel space operations, where the seq_file framework's next() iterator function returns NULL or error conditions that are not properly managed by the sg.c driver. When the iterator encounters these exceptional states, the corresponding memory allocations remain unreleased, creating a progressive consumption of available system memory. This behavior aligns with CWE-401, which specifically addresses improper handling of memory allocation and deallocation in software systems, particularly in kernel environments where resource management is critical. The flaw operates at the intersection of kernel memory management and procfs interface handling, where the expected iterative data presentation fails to account for error conditions that should trigger proper cleanup operations.
The operational impact of this vulnerability extends beyond simple resource exhaustion, as it provides local attackers with a straightforward method to degrade system performance and potentially render the system unusable. The memory consumption occurs gradually during repeated read operations, making it difficult to detect immediately but eventually leading to system instability and denial of service. This vulnerability particularly affects systems that rely heavily on SCSI device monitoring or have applications that continuously poll the /proc/scsi/sg/devices file for status information. The attack vector requires only local access to the system, making it accessible to any user with basic system privileges and significantly lowering the barrier to exploitation. From an ATT&CK perspective, this vulnerability maps to T1499.004, which covers network denial of service attacks through resource exhaustion, although the specific implementation targets local memory resources rather than network bandwidth.
Mitigation strategies for this vulnerability involve both immediate patching and operational hardening measures. The primary solution requires updating to Linux kernel versions 2.6.14 or later, where the memory leak has been addressed through improved error handling in the seq_file iterator implementation. System administrators should also implement monitoring for unusual memory consumption patterns and consider limiting access to the /proc/scsi/sg/devices file through file system permissions or process control mechanisms. Additionally, applications that require access to SCSI device information should be modified to minimize repeated reads or implement proper caching mechanisms to reduce the frequency of procfs access. The vulnerability underscores the importance of thorough error handling in kernel space code, particularly when dealing with iterator-based data presentation mechanisms that must account for various failure states and maintain proper resource cleanup regardless of execution path taken.