Linux Kernel Hygon CPU Initialization Division by Zero Vulnerability

A vulnerability in the Linux kernel's handling of Hygon CPUs can lead to a division by zero error during the early boot process. This issue arises because the Hygon-specific initialization routine for the CPU does not properly call a function that detects and configures resource monitoring properties. As a result, certain data needed for cache monitoring is uninitialized, causing a fault. This vulnerability affects Linux kernel versions that include the problematic Hygon initialization, specifically in the stable branch.

Impact

The vulnerability causes a division by zero fault, which can lead to a crash during the boot process on systems with Hygon CPUs and certain cache monitoring features enabled.

Reproduction

The vulnerability can be reproduced by booting a machine with a Hygon CPU that supports the cache quality monitoring features. The absence of the proper initialization call in the CPU's vendor-specific boot sequence will trigger the division by zero fault, causing the system to crash early in the boot process.

Remediation

Users can upgrade to a patched version of the Linux kernel where this vulnerability has been addressed. The specific commit that fixes this issue is available in the Linux kernel stable tree.