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.
References 6
https://git.kernel.org/stable/c/0dbc2e94b81df5a1264068b6ed3605c654b8afcb
416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/8953bdd1b9c0e748d5408d3d0b8e7aeee5c9cd41
416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/92895a14329cc9533e2a74a265214f690ba3851a
416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/b2326338dc683e8c1067c0cbf7a47986c4190902
416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/3cd611c9f1dbcc116c8af5112e3c1783c8cde2ae
416baaa9-dc9f-4396-8d5f-8c081fb06d67
https://git.kernel.org/stable/c/97d71ebee48cd1b29091762b3e5cca4f815dd84c
416baaa9-dc9f-4396-8d5f-8c081fb06d67