CVE-2024-35801: 
Linux Kernel vulnerability analysis and mitigation

CVE-2024-35801 affects the Linux kernel's x86/fpu subsystem. The vulnerability was discovered when a synchronization issue was found between the per-CPU xfd_state cache and MSR_IA32_XFD values. The issue was introduced by previous commits that implemented caching of MSR_IA32_XFD values to avoid unnecessary writes to the MSR (Kernel Git).

The vulnerability stems from a synchronization issue where during CPU hotplug, MSR_IA32_XFD is reset to init_fpstate.xfd to wipe out stale state, but the per-CPU cached xfd value is not reset accordingly. This desynchronization can cause xfd_update_state() to fail to update the MSR, potentially resulting in XRSTOR raising a #NM (Device Not Available) exception in kernel space, leading to a kernel crash (NVD). The vulnerability has been assigned a CVSS v3.1 base score of 7.8 (HIGH) with vector: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H (CISA-ADP).

When exploited, this vulnerability can cause a kernel crash due to XRSTOR raising a #NM exception in kernel space. This creates a denial of service condition affecting system stability and availability (NVD).

The vulnerability requires local access with low privileges and no user interaction to exploit. The attack complexity is considered low, making it relatively straightforward to trigger the vulnerability condition (CISA-ADP).

The vulnerability has been fixed by introducing xfd_set_state() function to write xfd_state together with MSR_IA32_XFD, ensuring synchronization between the cached state and MSR value. This fix has been implemented in various kernel versions through patches (Kernel Git).