CVE-2025-38613 in Linux
Summary
by MITRE • 08/19/2025
In the Linux kernel, the following vulnerability has been resolved:
staging: gpib: fix unset padding field copy back to userspace
The introduction of a padding field in the gpib_board_info_ioctl is showing up as initialized data on the stack frame being copyied back to userspace in function board_info_ioctl. The simplest fix is to initialize the entire struct to zero to ensure all unassigned padding fields are zero'd before being copied back to userspace.
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Analysis
by VulDB Data Team • 01/21/2026
The vulnerability identified as CVE-2025-38613 resides within the Linux kernel's staging subsystem, specifically affecting the gpib (General Purpose Interface Bus) driver component. This issue demonstrates a classic example of uninitialized memory exposure that can potentially lead to information disclosure or privilege escalation scenarios. The gpib driver facilitates communication with instruments connected via the IEEE 488.2 standard, commonly used in scientific and industrial measurement equipment. When the kernel processes ioctl commands related to board information, it encounters a problematic interaction between kernel and user space memory management that creates security implications through improper data handling.
The technical flaw manifests in the board_info_ioctl function where a padding field was introduced within the gpib_board_info_ioctl structure. During the copy operation from kernel space back to user space, this padding field contains uninitialized data from the stack frame that was not explicitly cleared. The stack frame memory contains remnants of previous operations or system state that should not be exposed to user applications. This represents a violation of the principle of least privilege and memory isolation that forms the foundation of secure kernel operation. The vulnerability stems from the fact that when structures containing padding fields are copied back to user space, these padding areas retain their previous contents rather than being properly initialized to zero.
The operational impact of this vulnerability extends beyond simple information disclosure, potentially creating avenues for attackers to gather sensitive kernel memory information that could aid in more sophisticated exploitation techniques. While the immediate threat may appear limited to exposure of uninitialized padding data, such issues often serve as stepping stones for attackers to build more complex attacks. The vulnerability affects systems running Linux kernels with the gpib driver enabled and could be particularly concerning in environments where security is paramount, such as scientific research facilities, manufacturing systems, or industrial control networks where gpib devices are commonly deployed. The issue demonstrates how seemingly minor code changes can introduce security implications that require careful consideration of memory management practices in kernel space.
The recommended mitigation strategy involves initializing the entire structure to zero before copying it back to user space, as implemented in the fix. This approach aligns with security best practices outlined in the CWE-1210 category for improper initialization of memory and follows the principle of defensive programming. The solution ensures that all padding fields within the structure are explicitly set to zero, eliminating the risk of exposing uninitialized memory contents. Organizations should prioritize applying the kernel updates that contain this fix and conduct thorough testing to ensure compatibility with existing gpib-based applications. This vulnerability also highlights the importance of regular security reviews of kernel subsystems and adherence to secure coding practices such as those recommended by the ATT&CK framework for kernel-mode operations, particularly in the area of privilege escalation and information disclosure techniques that could leverage uninitialized memory exposure.