Linux Kernel Hotplug CPU State Handling Vulnerability in HRTimers

A vulnerability in the Linux kernel's handling of CPU hotplug events can lead to incorrect assumptions about the state of high-resolution timers (HRTimers) on certain CPUs. When a CPU is unplugged and then reconnected, the system may mistakenly believe that the timer is already active, causing the clockevent device to miss the opportunity to switch to one-shot mode. This issue arises because the CPU's per-state information is not properly reset during the hotplug process, leaving behind outdated pointers that can disrupt timer management.

Impact

This vulnerability can cause high-resolution timers to be mismanaged on CPUs that undergo a hotplug unplug and replug cycle, leading to potential timing issues in the kernel's scheduling and event handling.

Remediation

Users can apply the latest patches from the official Linux kernel repository to address this vulnerability. Instructions for applying these patches can be found in the Linux kernel documentation.