CVE-2025-38712 in Linux
Summary
by MITRE • 09/04/2025
In the Linux kernel, the following vulnerability has been resolved:
hfsplus: don't use BUG_ON() in hfsplus_create_attributes_file()
When the volume header contains erroneous values that do not reflect the actual state of the filesystem, hfsplus_fill_super() assumes that the attributes file is not yet created, which later results in hitting BUG_ON() when hfsplus_create_attributes_file() is called. Replace this BUG_ON() with -EIO error with a message to suggest running fsck tool.
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Analysis
by VulDB Data Team • 02/10/2026
The vulnerability described in CVE-2025-38712 represents a critical flaw in the Linux kernel's HFS+ filesystem implementation that could lead to system instability and potential denial of service conditions. This issue specifically affects the hfsplus filesystem driver within the Linux kernel, where improper error handling mechanisms can cause unexpected system behavior when encountering corrupted or inconsistent filesystem metadata. The vulnerability stems from the use of BUG_ON() macro in the hfsplus_create_attributes_file() function, which is designed to terminate the kernel execution when certain conditions are met, rather than gracefully handling error states that may occur during normal filesystem operations.
The technical flaw manifests when the volume header contains erroneous values that do not accurately reflect the actual state of the filesystem. During the filesystem mounting process, the hfsplus_fill_super() function makes incorrect assumptions about the attributes file state, leading to a cascade of operations that ultimately trigger the problematic BUG_ON() call. This condition typically occurs when filesystem metadata is corrupted or when there are inconsistencies between the header information and the actual filesystem structure. The BUG_ON() macro, which is intended for debugging and development purposes, should never be present in production code paths as it causes immediate kernel panic and system termination, making the system completely unresponsive to further operations.
From an operational impact perspective, this vulnerability poses significant risks to systems relying on HFS+ filesystems, particularly those running on Apple hardware or systems that have HFS+ support enabled. The immediate consequence is a kernel panic that results in system crash and potential data loss, as the kernel terminates execution rather than attempting to recover from the inconsistent state. This behavior violates the fundamental principle of robust error handling in kernel space, where systems should gracefully handle corrupted data rather than terminating execution. The vulnerability affects systems that mount HFS+ filesystems, including those using Apple's HFS+ implementation on Linux, which can occur in dual-boot environments, external storage devices, or systems that maintain compatibility with Apple filesystems.
The recommended mitigation strategy involves replacing the problematic BUG_ON() call with proper error handling that returns -EIO error code along with a descriptive message directing users to run the fsck tool for filesystem repair. This approach aligns with the principle of graceful degradation and follows established best practices for kernel error handling as outlined in the Linux kernel documentation. The fix ensures that when filesystem inconsistencies are detected, the system can continue operating and provide users with actionable information rather than abruptly terminating. This remediation approach also conforms to the ATT&CK framework's concept of system compromise through kernel-level vulnerabilities, where proper error handling prevents exploitation of such conditions by malicious actors who might attempt to trigger kernel panics for denial of service attacks. The solution addresses the underlying CWE-754 weakness related to improper handling of exceptional conditions in kernel code, ensuring that filesystem drivers maintain stability even when encountering corrupted data structures.
The implementation of this fix demonstrates the importance of proper defensive programming practices in kernel space, where assumptions about system state must be validated before proceeding with operations. The change ensures that filesystem drivers properly validate their assumptions about metadata consistency and handle error conditions gracefully. This vulnerability highlights the critical need for thorough testing of error paths in kernel modules, particularly those dealing with filesystem metadata validation and recovery operations. The resolution also emphasizes the importance of maintaining backward compatibility while ensuring system stability, as the error message provides clear guidance to users about the appropriate recovery actions. This approach to vulnerability remediation reflects the broader security principles of building resilient systems that can handle unexpected conditions without compromising overall system availability, which is essential for maintaining the integrity of the Linux kernel's filesystem subsystem and preventing potential exploitation scenarios that could arise from such kernel-level flaws.