CVE-2010-4163 in Linux
Summary
by MITRE
The blk_rq_map_user_iov function in block/blk-map.c in the Linux kernel before 2.6.36.2 allows local users to cause a denial of service (panic) via a zero-length I/O request in a device ioctl to a SCSI device.
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Analysis
by VulDB Data Team • 07/01/2024
The vulnerability identified as CVE-2010-4163 represents a critical denial of service flaw within the Linux kernel's block layer subsystem. This issue affects versions prior to 2.6.36.2 and specifically targets the blk_rq_map_user_iov function located in the block/blk-map.c file. The vulnerability arises from insufficient input validation when processing I/O requests, creating a scenario where malicious local users can exploit the system's handling of zero-length I/O operations to trigger kernel panics and system crashes. The flaw is particularly concerning because it operates at the kernel level, providing attackers with direct access to system stability without requiring elevated privileges beyond local user access.
The technical implementation of this vulnerability stems from how the kernel processes device I/O requests through the SCSI subsystem. When a zero-length I/O request is submitted via a device ioctl to a SCSI device, the blk_rq_map_user_iov function fails to properly validate the request parameters before attempting to map the I/O vector. This validation gap allows the function to proceed with processing a request that contains no actual data, leading to memory corruption and subsequent kernel panic conditions. The issue manifests as a failure in the kernel's request mapping logic, where the system attempts to allocate resources for an invalid I/O operation that contains no meaningful data to process, ultimately causing the kernel to become unstable and crash.
From an operational perspective, this vulnerability presents significant risks to system availability and stability. Local users can exploit this flaw to cause unexpected system panics, effectively creating a denial of service condition that can disrupt normal system operations. The impact extends beyond simple service interruption as kernel panics can lead to data loss, system downtime, and potential security implications if the crash occurs during critical operations. The vulnerability is particularly dangerous in server environments where system uptime is critical, as it allows any local user to potentially destabilize the entire system. Additionally, the nature of the exploit means that it can be triggered repeatedly, making it a persistent threat to system reliability and availability.
The vulnerability maps directly to CWE-129, which describes improper validation of array index values, and aligns with ATT&CK technique T1499.004 for network denial of service. The attack surface is limited to local users who have access to the system and can submit device ioctls to SCSI devices, but the impact is severe enough that it requires immediate attention. The exploitation process involves crafting a zero-length I/O request through a device ioctl call, which bypasses normal input validation mechanisms and directly targets the kernel's I/O mapping function. This vulnerability demonstrates the importance of robust input validation in kernel space operations and highlights the potential consequences of inadequate parameter checking in system-critical components.
Mitigation strategies for CVE-2010-4163 focus primarily on patching affected systems with kernel versions 2.6.36.2 or later, which contain the necessary fixes to properly validate I/O request parameters. System administrators should prioritize updating their kernel versions and ensure that all systems running vulnerable kernel versions are patched immediately. Additional protective measures include implementing proper access controls to limit local user privileges, monitoring for unusual I/O operations, and maintaining robust system logging to detect potential exploitation attempts. Network segmentation and privilege separation can help reduce the attack surface, while regular security audits should verify that all kernel components are properly updated and that no vulnerable versions remain in production environments. Organizations should also consider implementing intrusion detection systems that can identify suspicious I/O patterns that might indicate exploitation attempts.