Linux Kernel SiFive PLIC Affinity Change Vulnerability Causes Interrupt Handling Freeze

A vulnerability in the Linux kernel's handling of interrupts with the SiFive PLIC (Programmable Interrupt Controller) can lead to a frozen interrupt state. This issue arises when the affinity setting of an interrupt is changed while it is still being processed, causing the interrupt to be ignored and not properly completed. The problem can be reproduced by generating a high volume of interrupts and simultaneously altering the interrupt's affinity, which quickly freezes the affected interrupt line.

Impact

The vulnerability can cause interrupts to be lost or not processed correctly, leading to a freeze in the system's response to certain events or conditions that rely on those interrupts.

Reproduction

The issue can be reproduced by dumping a large file to a UART port, which generates a significant number of interrupts. While this process is ongoing, the affinity setting of the UART interrupt can be changed, causing the UART port to freeze almost immediately.

Remediation

Users can apply the latest patches available in the Linux kernel stable tree to address this vulnerability.