OpenBSD Journal

More Mitigations for (potential) CPU Vulnerabilities

Contributed by rueda on from the cheap, fast, reliable: pick any tw^H^H - oh, crap! dept.

There have been more developments in the continuing work mitigating against (Intel®, and potentially other) CPU vulnerabilities…

Philip Guenther (guenther@) committed the following:

Module name:	src
Changes by:	2018/06/14 13:57:29

Modified files:
	sys/arch/amd64/include: frameasm.h 
	sys/arch/amd64/amd64: locore.S vector.S 

Log message:
Clear the GPRs when entering the kernel from userspace so that
user-controlled values can't take part in speculative execution in
the kernel down paths that end up "not taken" but that may cause
user-visible effects (cache, etc).

prodded by dragonflybsd commit 9474cbef7fcb61cd268019694d94db6a75af7dbe
ok deraadt@ kettenis@

(DragonFly BSD gained FPU protection, and enabled NX for PROT_READ by default, too.)

A message to tech@ from Theo de Raadt (deraadt@) included:

ps. Disable Intel Hyper-Threading where not needed, until we all know more.

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