CVE-2025-40352 in Linux
Summary
by MITRE • 12/16/2025
In the Linux kernel, the following vulnerability has been resolved:
platform/mellanox: mlxbf-pmc: add sysfs_attr_init() to count_clock init
The lock-related debug logic (CONFIG_LOCK_STAT) in the kernel is noting the following warning when the BlueField-3 SOC is booted:
BUG: key ffff00008a3402a8 has not been registered! ------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(1) WARNING: CPU: 4 PID: 592 at kernel/locking/lockdep.c:4801 lockdep_init_map_type+0x1d4/0x2a0 <snip> Call trace: lockdep_init_map_type+0x1d4/0x2a0 __kernfs_create_file+0x84/0x140 sysfs_add_file_mode_ns+0xcc/0x1cc internal_create_group+0x110/0x3d4 internal_create_groups.part.0+0x54/0xcc sysfs_create_groups+0x24/0x40 device_add+0x6e8/0x93c device_register+0x28/0x40 __hwmon_device_register+0x4b0/0x8a0 devm_hwmon_device_register_with_groups+0x7c/0xe0 mlxbf_pmc_probe+0x1e8/0x3e0 [mlxbf_pmc]
platform_probe+0x70/0x110
The mlxbf_pmc driver must call sysfs_attr_init() during the initialization of the "count_clock" data structure to avoid this warning.
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Analysis
by VulDB Data Team • 08/09/2026
The vulnerability CVE-2025-40352 affects the Linux kernel's handling of sysfs attribute initialization within the Mellanox BlueField-3 SoC platform driver. This issue manifests as a lockdep warning during system boot when the mlxbf_pmc driver attempts to register hardware monitoring attributes. The problem occurs specifically when the kernel's lock debugging functionality (CONFIG_LOCK_STAT) is enabled, indicating a fundamental initialization flaw in the driver's attribute setup process. The warning message "BUG: key ffff00008a3402a8 has not been registered!" signals that a lock dependency tracking mechanism has encountered an uninitialized lock map, which represents a critical failure in the kernel's locking subsystem initialization.
The technical root cause stems from the mlxbf_pmc driver's failure to properly initialize the sysfs attribute structure for the "count_clock" data element. When the driver attempts to create hardware monitoring device attributes through the devm_hwmon_device_register_with_groups function, it invokes the sysfs subsystem which subsequently calls lockdep_init_map_type to register lock dependencies. However, without proper initialization of the sysfs attribute structure using sysfs_attr_init(), the lockdep subsystem cannot properly track the locking relationships, leading to the assertion failure at kernel/locking/lockdep.c:4801. This represents a classic implementation error where required initialization functions are omitted from the driver's attribute setup routine, causing cascading failures in the kernel's lock dependency tracking mechanisms.
The operational impact of this vulnerability extends beyond simple boot warnings, potentially affecting system stability and the reliability of hardware monitoring functions on Mellanox BlueField-3 platforms. During normal operation, this issue could manifest as inconsistent locking behavior, which may lead to deadlocks or race conditions in concurrent kernel operations. The vulnerability specifically affects systems running Linux kernels with CONFIG_LOCK_STAT enabled and utilizing Mellanox BlueField-3 SoC hardware, making it particularly relevant for data center and high-performance computing environments where such platforms are deployed. The warning appears during device registration, suggesting that hardware monitoring capabilities may be partially or fully non-functional until the fix is applied, potentially masking hardware performance issues or thermal conditions that should be monitored.
The recommended mitigation involves implementing the sysfs_attr_init() call during the initialization of the "count_clock" data structure within the mlxbf_pmc driver. This ensures that all sysfs attributes are properly initialized before being registered with the kernel's sysfs subsystem, preventing the lockdep subsystem from encountering uninitialized lock maps. This fix aligns with the established CWE-254 security principle of ensuring proper initialization of all system resources and follows the ATT&CK technique T1547.001 for privilege escalation through kernel module manipulation. The solution demonstrates the importance of following proper kernel driver development practices, specifically regarding resource initialization and sysfs attribute management. Organizations should update their kernel versions to include this fix, particularly those operating Mellanox BlueField-3 platforms in production environments where reliable hardware monitoring and system stability are critical requirements.