Intel processors (L1 terminal fault, OS/SMM): The OS-level variant of L1 terminal fault: a local user can speculatively

Impact

The OS-level variant of L1 terminal fault: a local user can speculatively read data present in the L1 cache belonging to the kernel or to system-management memory, by faulting on a carefully crafted page-table entry. Sits alongside the hypervisor-level L1TF variant as the reason page-table entry inversion exists in every modern kernel.

Who can reach it

Any local unprivileged code on an affected processor.

What to do

Microcode update plus the kernel's PTE-inversion mitigation, then reboot. Microcode is late-loadable at boot without an OEM BIOS release. Verify with the kernel's l1tf sysfs vulnerability file after reboot rather than assuming.

References