CVE-2026-74389 in Linux
Summary
by MITRE • 08/15/2026
In the Linux kernel, the following vulnerability has been resolved:
RDMA/hns: Fix log flood after cmd_mbox failure
hns_roce_cmd_mbox() is the command interface between driver and hardware. When hardware is abnormal, the unlimited error printings after hns_roce_cmd_mbox() failure will cause log flood and even system crash.
Replace ibdev_err() and ibdev_warn() with their ratelimited versions in the error handling path after hns_roce_cmd_mbox() (and its wrappers hns_roce_create_hw_ctx/hns_roce_destroy_hw_ctx) fails.
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Analysis
by VulDB Data Team • 08/15/2026
The vulnerability identified in the Linux kernel's RDMA/hns subsystem represents a critical logging issue that can lead to system instability and potential denial of service conditions. This flaw manifests within the hns_roce_cmd_mbox() function which serves as the primary command interface between the driver and hardware components in Huawei's networking infrastructure. The function acts as a bridge for communication between software drivers and hardware accelerators, specifically within the HiSilicon Networking Subsystem that handles RDMA operations for high-performance computing environments.
When hardware abnormalities occur during command execution, the current implementation fails to properly manage error message output by utilizing non-ratelimited logging functions. This results in unlimited error printings that flood system logs with repetitive diagnostic messages. The excessive logging volume can overwhelm system resources and potentially lead to complete system crash conditions, particularly when multiple simultaneous failures occur or when hardware issues persist over extended periods. The vulnerability directly impacts the stability of systems relying on RDMA functionality for high-speed data transmission in data center environments.
The technical implementation flaw stems from improper error handling within the driver's error recovery path where ibdev_err() and ibdev_warn() functions are called without rate limiting mechanisms. These logging functions generate verbose output regardless of repetition frequency, creating a scenario where identical or similar error messages are continuously logged to kernel buffers. According to CWE-704, this represents an insufficient logging issue where the system fails to implement proper rate limiting for error reporting functions. The problem is particularly severe in production environments where excessive logging can consume significant memory resources and impact overall system performance.
This vulnerability directly aligns with ATT&CK technique T1490, which describes "Inhibit System Recovery" through resource exhaustion or system instability. The unlimited logging behavior creates a condition where the system's logging subsystem becomes overwhelmed, potentially causing cascading failures that affect other critical system components. The operational impact extends beyond simple log flooding to include potential complete system crashes, making this a high-severity issue for enterprise deployments using Huawei networking hardware in mission-critical applications.
The recommended mitigation strategy involves replacing the non-ratelimited ibdev_err() and ibdev_warn() calls with their ratelimited counterparts within the error handling path of hns_roce_cmd_mbox() and its associated wrapper functions. This approach aligns with industry best practices for preventing log flooding and resource exhaustion attacks as outlined in various security frameworks and kernel hardening guidelines. The solution specifically addresses the root cause by implementing proper rate limiting mechanisms that prevent excessive logging while still maintaining critical error visibility for system administrators and support personnel. This modification ensures that error messages remain informative without overwhelming system resources, thereby preserving system stability and preventing potential denial of service conditions that could affect high-performance computing clusters relying on RDMA connectivity.