CVE-2025-38277 in Linux
Summary
by MITRE • 07/10/2025
In the Linux kernel, the following vulnerability has been resolved:
mtd: nand: ecc-mxic: Fix use of uninitialized variable ret
If ctx->steps is zero, the loop processing ECC steps is skipped, and the variable ret remains uninitialized. It is later checked and returned, which leads to undefined behavior and may cause unpredictable results in user space or kernel crashes.
This scenario can be triggered in edge cases such as misconfigured geometry, ECC engine misuse, or if ctx->steps is not validated after initialization.
Initialize ret to zero before the loop to ensure correct and safe behavior regardless of the ctx->steps value.
Found by Linux Verification Center (linuxtesting.org) with SVACE.
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Analysis
by VulDB Data Team • 12/19/2025
The vulnerability described in CVE-2025-38277 represents a critical uninitialized variable issue within the Linux kernel's MTD (Memory Technology Device) subsystem, specifically affecting the NAND flash memory driver with MXIC ECC (Error Correction Code) support. This flaw exists in the ecc-mxic.c driver component that handles error correction for NAND flash devices manufactured by MXIC. The vulnerability arises from improper initialization of the return variable ret within the ECC processing loop, creating a pathway for undefined behavior that can manifest as system instability or crashes.
The technical flaw occurs when the context structure ctx->steps is initialized to zero, which causes the ECC processing loop to be completely skipped. During this skip, the variable ret remains uninitialized and subsequently gets checked and returned to the calling function. This uninitialized variable condition violates fundamental programming practices and creates a potential attack surface where malicious actors could exploit the undefined behavior. The issue is particularly concerning because it operates at the kernel level where such undefined behavior can lead to system crashes, data corruption, or potentially privilege escalation scenarios. The vulnerability is categorized under CWE-457 as "Use of Uninitialized Variable" which directly maps to the core problem of using a variable without proper initialization before its first use.
Operational impact of this vulnerability extends beyond simple system crashes to potentially compromise the integrity of NAND flash operations in embedded systems, storage devices, and embedded platforms that rely on MXIC NAND flash controllers. The vulnerability can be triggered through various edge cases including misconfigured NAND geometry parameters, improper ECC engine initialization, or when the driver fails to validate the ctx->steps parameter after initialization. These conditions may occur in production environments where hardware configurations are not properly validated or during firmware updates where initialization sequences are interrupted. The Linux Verification Center's discovery through SVACE static analysis tools indicates this vulnerability could be present in various kernel versions and hardware configurations, making it a widespread concern for system administrators managing embedded Linux systems. The unpredictable nature of uninitialized variable behavior means that impacts could range from occasional system hangs to complete system failures during NAND read/write operations.
The recommended mitigation strategy involves implementing proper variable initialization before entering the ECC processing loop. The fix requires initializing the ret variable to zero before the loop executes, ensuring that regardless of the ctx->steps value, the function will always return a predictable and valid result. This approach directly addresses the root cause by preventing the use of uninitialized memory and aligns with best practices for kernel programming and security hardening. System administrators should prioritize updating to kernel versions containing this fix, particularly in embedded systems, industrial control systems, and IoT devices where NAND flash memory is utilized. The fix also demonstrates the importance of comprehensive static analysis tools like SVACE in identifying subtle but critical kernel vulnerabilities that could otherwise remain undetected until exploitation occurs. Organizations should implement regular kernel updates and vulnerability scanning procedures to prevent exploitation of similar uninitialized variable issues that could exist in other kernel subsystems or drivers.