Messages in this thread | | | Date | Wed, 3 Jan 2018 16:09:27 -0800 | From | Andi Kleen <> | Subject | Re: Avoid speculative indirect calls in kernel |
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Hi Linus,
On Wed, Jan 03, 2018 at 03:51:35PM -0800, Linus Torvalds wrote: > On Wed, Jan 3, 2018 at 3:09 PM, Andi Kleen <andi@firstfloor.org> wrote: > > This is a fix for Variant 2 in > > https://googleprojectzero.blogspot.com/2018/01/reading-privileged-memory-with-side.html > > > > Any speculative indirect calls in the kernel can be tricked > > to execute any kernel code, which may allow side channel > > attacks that can leak arbitrary kernel data. > > Why is this all done without any configuration options?
I was thinking of a config option, but I was struggling with a name.
CONFIG_INSECURE_KERNEL, CONFIG_LEAK_MEMORY?
And should it be positive or negative?
So I opted to be secure uncontionally.
It would be simple to add however, all hooks are either in the Makefile or in asm/jump-asm.h
> - these workarounds should have a way to disable them. >
There will be soon patches to add other ways and they have a way to patch out most of the retpoline overhead at runtime (basically replace the trampoline with a pure ret)
We just wanted to get the retpoline code out first because it's the most basic and widest applicable fix.
-Andi
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