arch/x86/entry/entry_64.S in the Linux kernel before 4.1.6 on the x86_64 platform does not properly determine when nested NMI processing is occurring, which allows local users to cause a denial of service (skipped NMI) by modifying the rsp register, issuing a syscall instruction, and triggering an NMI.
Exploitability
AV:LAC:LAu:NImpact
C:NI:NA:P2.1/AV:L/AC:L/Au:N/C:N/I:N/A:P