CVE-2021-47075 in Linux
Summary
by MITRE • 03/02/2024
In the Linux kernel, the following vulnerability has been resolved:
nvmet: fix memory leak in nvmet_alloc_ctrl()
When creating ctrl in nvmet_alloc_ctrl(), if the cntlid_min is larger than cntlid_max of the subsystem, and jumps to the "out_free_changed_ns_list" label, but the ctrl->sqs lack of be freed. Fix this by jumping to the "out_free_sqs" label.
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Analysis
by VulDB Data Team • 11/07/2024
The vulnerability identified as CVE-2021-47075 represents a memory leak within the Linux kernel's NVMe over Fabrics target implementation, specifically affecting the nvmet_alloc_ctrl() function. This flaw exists in the nvme target subsystem which handles NVMe traffic over fabrics, enabling storage communication between NVMe hosts and targets across networked environments. The issue manifests during controller creation when the subsystem's controller identifier range validation fails, creating a path where memory allocated for controller queue structures remains unreleased.
The technical root cause stems from improper error handling logic within the nvmet_alloc_ctrl() function where the code path fails to properly clean up allocated resources. When the cntlid_min parameter exceeds the cntlid_max parameter of the subsystem, the function attempts to jump to the "out_free_changed_ns_list" error label but neglects to free the controller's queue structures stored in ctrl->sqs. This represents a classic resource management flaw where allocated memory is not properly deallocated during error conditions, leading to memory leakage that can accumulate over time.
The operational impact of this vulnerability extends beyond simple memory consumption issues, as persistent memory leaks can lead to system performance degradation and potential denial of service conditions. In environments where NVMe over Fabrics targets are heavily utilized, such as enterprise storage arrays or data center infrastructures, this memory leak can progressively consume available system resources, potentially causing system instability or service interruption. The vulnerability affects systems running Linux kernel versions prior to the fix, particularly impacting storage infrastructure components that rely on NVMe target functionality for networked storage operations.
Security implications of this memory leak vulnerability align with CWE-401, which addresses improper handling of memory allocation failures and resource leaks in software systems. The flaw demonstrates a failure in proper resource cleanup during exceptional conditions, representing a weakness in the kernel's memory management practices for fabric storage protocols. From an ATT&CK perspective, this vulnerability could enable adversaries to perform resource exhaustion attacks against storage systems, potentially leading to service disruption or system instability that could impact availability and system integrity within storage infrastructure environments.
The fix for CVE-2021-47075 involves modifying the error handling path within nvmet_alloc_ctrl() to ensure proper resource cleanup by redirecting error flow to the "out_free_sqs" label instead of the incorrect "out_free_changed_ns_list" label. This correction ensures that when controller identifier validation fails, all allocated controller queue structures are properly freed before the function exits. System administrators should update to kernel versions containing this fix to prevent memory leakage and maintain system stability. The remediation approach follows standard secure coding practices for resource management, ensuring that all allocated resources are properly deallocated regardless of execution path taken during error conditions.