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Linux Kernel Userfaultfd Migration Entry Handling Vulnerability Causes Crash

Vulnerability

A vulnerability in the Linux kernel's userfaultfd implementation can lead to a crash when the UFFDIO_MOVE operation encounters a migration PMD (Page Map Directory) entry. The issue arises because the operation attempts to access a folio (a unit of memory management) associated with the migration entry, which is not valid. This vulnerability affects several versions of the Linux kernel.

Impact

The vulnerability can cause a system crash, disrupting normal operations and potentially leading to a denial of service.

Reproduction

To reproduce this vulnerability, use the UFFDIO_MOVE operation in a context where the PMD entry is a migration entry. The operation will crash the system due to the improper handling of the migration entry.

Remediation

Users can upgrade to the latest version of the Linux kernel where this vulnerability has been addressed.

Added: Sep 4, 2025, 5:53 PM
Updated: Sep 4, 2025, 5:53 PM

Vulnerability Rating

Custom Algorithm
spread
9.0
impact
2.5
exploitability
4.3
remediation
7.7
relevance
0.5
threat
4.8
urgency
2.9
incentive
1.7

Our algorithm analyzes dozens of metrics to generate these 8 key vulnerability categories, which are then combined to calculate the overall risk score.