CVE-2010-4668 in Linux
Summary
by MITRE
The blk_rq_map_user_iov function in block/blk-map.c in the Linux kernel before 2.6.37-rc7 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, related to an unaligned map. NOTE: this vulnerability exists because of an incomplete fix for CVE-2010-4163.
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Analysis
by VulDB Data Team • 10/08/2021
The vulnerability described in CVE-2010-4668 represents a critical denial of service weakness in the Linux kernel's block layer subsystem that specifically targets the handling of I/O requests for SCSI devices. This issue affects Linux kernel versions prior to 2.6.37-rc7 and stems from an incomplete remediation of a previously identified vulnerability, CVE-2010-4163, which demonstrates the complexity of kernel security fixes and the potential for remediation gaps that can leave systems exposed to exploitation.
The technical flaw manifests within the blk_rq_map_user_iov function located in the block/blk-map.c file of the kernel source code. This function is responsible for mapping user-space I/O requests to kernel-space block requests when dealing with SCSI devices through device ioctls. The vulnerability occurs when processing zero-length I/O requests that are improperly aligned, creating a scenario where the kernel's memory management and request mapping logic fails to handle the edge case correctly. The unaligned map condition specifically refers to how the kernel calculates and manages memory mappings for I/O operations when the request boundaries do not align with expected memory page boundaries.
The operational impact of this vulnerability is significant as it allows local users to trigger a kernel panic, effectively causing a system-wide denial of service condition. When a malicious user crafts a specific device ioctl command with a zero-length I/O request against a SCSI device, the kernel's response to this malformed request causes a critical failure in the block layer's request processing mechanism. This panic results in the kernel terminating execution and the system becoming unresponsive, requiring manual intervention or reboot to restore normal operation. The local nature of this vulnerability means that an attacker must already have access to the system, but the impact is severe enough to warrant immediate attention.
This vulnerability aligns with CWE-121 and CWE-125 categories related to buffer overflow conditions and improper access to memory locations, while also demonstrating characteristics of ATT&CK technique T1499.004 for network denial of service. The incomplete fix for CVE-2010-4163 indicates a pattern where security patches may not fully address all edge cases in complex kernel subsystems, leaving residual vulnerabilities that can be exploited. The issue specifically impacts the Linux kernel's block I/O subsystem and SCSI device handling, making it particularly relevant to systems that rely heavily on storage I/O operations and enterprise storage solutions that utilize SCSI interfaces. Organizations should prioritize updating to kernel versions 2.6.37-rc7 or later to mitigate this vulnerability, as the fix addresses the root cause of the unaligned memory mapping issue and prevents the kernel panic condition from occurring during processing of malformed I/O requests.