Messages in this thread | | | Date | Wed, 2 Sep 2020 18:23:30 +0100 | From | Mark Rutland <> | Subject | Re: [PATCH] x86/uaccess: Use pointer masking to limit uaccess speculation |
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On Wed, Sep 02, 2020 at 03:32:31PM +0200, Christoph Hellwig wrote: > On Wed, Sep 02, 2020 at 12:43:48PM +0100, Mark Rutland wrote: > > I'll see what I can do. > > > > At first glance it looks like we might need to flesh out or refactor the > > arm64 kernel maccess routines first (since we want the user maccess > > routines to use LDTR/STTR instructions that can't access kernel memory), > > but after that I think the rest is largely mechanical. > > Yes, the first thing is to implement __get_kernel_nofaul and > __put_kernel_nofault. I think they should mostly look like the existing > non-UAO versions of get_user and put_user with a fixed address space > limit.
I've pushed an initial/incomplete/WIP stab (just the kernel accessors) to:
https://git.kernel.org/pub/scm/linux/kernel/git/mark/linux.git/log/?h=arm64/set_fs-removal
... and doing that made it clear that the necessary arm64 rework is a bit more fractal than I thought (e.g. SDEI bits), so it might be a short while before I post a series.
It might be handy to have a stable branch with the common bits so that the arm64 rework could go via the arm64 tree in case there's any fallout.
Thanks for all of this!
Mark.
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