CVE-2024-36936: 
Linux Kernel vulnerability analysis and mitigation

CVE-2024-36936 addresses a soft lockup vulnerability in the Linux kernel's EFI unaccepted memory handling. The issue was discovered when a previous fix (commit 50e782a86c98) that addressed parallel memory acceptance caused intermittent soft lockups in TD guest systems with large memory configurations and a 1-second softlockup timeout setting (Kernel Commit).

The vulnerability occurs when local IRQ is enabled at the end of accept_memory(). The softlockup detector identifies that the watchdog on a single CPU hasn't been fed for an extended period. While other CPUs aren't blocked by spinlock, the current CPU might be stuck with local IRQ disabled, affecting both NMI watchdog and softlockup detection. The issue manifests in the call trace through various kernel functions, including _raw_spin_unlock_irqrestore, hrtimer_interrupt, and memory management routines (Kernel Commit).

When triggered, this vulnerability can cause system soft lockups, particularly in TD guest environments with large memory configurations. The issue affects the system's stability and can impact the normal operation of memory acceptance processes (Kernel Commit).

The vulnerability is triggered during memory acceptance operations in specific configurations, particularly affecting TD guest systems with large memory allocations and 1-second softlockup timeout settings. It's primarily a stability issue rather than a security exploit (Kernel Commit).

The issue has been fixed by adding a call to touch_softlockup_watchdog() at the end of accept_memory(), which gives the softlockup detector a flag to skip the timeout check during this stage. This solution was implemented after recognizing that memory accept operations could be time-costly, based on similar previous reports (Kernel Commit, Ubuntu Security).