In the Linux kernel, the following vulnerability has been resolved: efivarfs: Rate limit statfs() handler Ravi reports that statfs() may be called by unprivileged users on the efivarfs mount point, which may result in a flood of calls to the QueryVariableInfo() runtime service. These calls are disproportionately costly on x86 systems where the variable store is backed by SMM, as each SMM entry requires a rendez-vous of all the CPUs. So rate limit the calls to QueryVariableInfo() at twice per second, and return the most recently obtained value for calls that are elided.
https://git.kernel.org/stable/c/b2326338dc683e8c1067c0cbf7a47986c4190902
https://git.kernel.org/stable/c/97d71ebee48cd1b29091762b3e5cca4f815dd84c
https://git.kernel.org/stable/c/92895a14329cc9533e2a74a265214f690ba3851a
https://git.kernel.org/stable/c/8953bdd1b9c0e748d5408d3d0b8e7aeee5c9cd41
https://git.kernel.org/stable/c/3cd611c9f1dbcc116c8af5112e3c1783c8cde2ae
https://git.kernel.org/stable/c/0dbc2e94b81df5a1264068b6ed3605c654b8afcb