Intel processors (rogue data cache load): MULTI-TENANT ISOLATION: Meltdown: unprivileged code reads kernel memory

Impact

MULTI-TENANT ISOLATION: Meltdown: unprivileged code reads kernel memory - and on affected parts, memory belonging to other tenants mapped into the kernel's direct map - by exploiting out-of-order execution past a permission check. The mitigation, kernel page-table isolation, is the reason every syscall on affected hardware got measurably slower.

Who can reach it

Any local unprivileged code on an affected processor.

What to do

Kernel page-table isolation (KPTI/PTI), shipped in the kernel; take the kernel update and reboot. Newer silicon fixes it in hardware. No microcode or BIOS component for the mitigation itself. Expect a syscall-heavy throughput regression on affected parts - that is the fix working.

References